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Diversity in Living Organisms- 2 - Free MCQ Practice Test with solutions,
MCQ Practice Test & Solutions: Test: Diversity in Living Organisms- 2 (25 Questions)
You can prepare effectively for UPSC General Science(Prelims) by IRS Divey Sethi with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Diversity in Living Organisms- 2". These 25 questions have been designed by the experts with the latest curriculum of UPSC 2026, to help you master the concept.
Test Highlights:
- - Format: Multiple Choice Questions (MCQ)
- - Duration: 25 minutes
- - Number of Questions: 25
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Test: Diversity in Living Organisms- 2 - Question 1
A unit of protoplasm having a nucleus and covered by plasmalemma is called :-
Detailed Solution: Question 1
A cytoplast is a medical term which is defined as cell membrane plus cytoplasm. It is occasionally used to describe a cell in which the nucleus has been removed. Protoplasm = Cytoplasm + Nucleoplasm. Protoplast = Protoplasm + Plasma membrane.
Detailed Solution: Question 2
Strasburger coined the terms cytoplasm and Nucleoplasm. Cytoplasm occurs around the Nucleus and inside the plasma membrane containing Various Organnels.
Test: Diversity in Living Organisms- 2 - Question 3
Which of the following is correct for prokaryotic ribosome :-
Detailed Solution: Question 3
Prokaryotic Ribosome:
- Prokaryotic ribosomes are the ribosomes found in prokaryotic cells, which include bacteria and archaea.
- They are responsible for protein synthesis in these organisms.
- Prokaryotic ribosomes are composed of two subunits: the large subunit (50S) and the small subunit (30S).
- These subunits dissociate from each other during certain stages of protein synthesis.
- The dissociation allows the ribosome to interact with various components involved in translation, such as mRNA and tRNA.
- The dissociation of prokaryotic ribosomes into 50S and 30S subunits is a crucial step in the initiation of protein synthesis.
- The 30S subunit recognizes the start codon on the mRNA, while the 50S subunit joins to form the complete ribosome for protein synthesis to occur.
- Once the protein synthesis is complete, the ribosomal subunits can dissociate again for further rounds of translation.
- Therefore, option A, "it dissociates into 50S and 30S," is the correct answer for prokaryotic ribosomes.
- Prokaryotic ribosomes are the ribosomes found in prokaryotic cells, which include bacteria and archaea.
- They are responsible for protein synthesis in these organisms.
- Prokaryotic ribosomes are composed of two subunits: the large subunit (50S) and the small subunit (30S).
- These subunits dissociate from each other during certain stages of protein synthesis.
- The dissociation allows the ribosome to interact with various components involved in translation, such as mRNA and tRNA.
- The dissociation of prokaryotic ribosomes into 50S and 30S subunits is a crucial step in the initiation of protein synthesis.
- The 30S subunit recognizes the start codon on the mRNA, while the 50S subunit joins to form the complete ribosome for protein synthesis to occur.
- Once the protein synthesis is complete, the ribosomal subunits can dissociate again for further rounds of translation.
- Therefore, option A, "it dissociates into 50S and 30S," is the correct answer for prokaryotic ribosomes.
Test: Diversity in Living Organisms- 2 - Question 4
Golgi apparatus takes part in synthesis of :-
Detailed Solution: Question 4
Golgi apparatus takes part in synthesis of:
- Glycolipids: The Golgi apparatus plays a crucial role in the synthesis of glycolipids. It receives lipids from the endoplasmic reticulum and modifies them by adding carbohydrate groups to produce glycolipids.
- Glycoproteins: The Golgi apparatus is responsible for the synthesis and modification of glycoproteins. It receives proteins from the endoplasmic reticulum and adds carbohydrate groups to them, creating glycoproteins.
- Hormones: The Golgi apparatus is involved in the synthesis and packaging of hormones. It receives newly synthesized hormones from the endoplasmic reticulum and modifies them before they are packaged into vesicles and transported to their final destinations.
- All of the above: The Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones. It is a crucial organelle in the secretory pathway of cells and plays a vital role in the processing, sorting, and packaging of various molecules.
In conclusion, the Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones, making option D, "All of the above," the correct answer.
- Glycolipids: The Golgi apparatus plays a crucial role in the synthesis of glycolipids. It receives lipids from the endoplasmic reticulum and modifies them by adding carbohydrate groups to produce glycolipids.
- Glycoproteins: The Golgi apparatus is responsible for the synthesis and modification of glycoproteins. It receives proteins from the endoplasmic reticulum and adds carbohydrate groups to them, creating glycoproteins.
- Hormones: The Golgi apparatus is involved in the synthesis and packaging of hormones. It receives newly synthesized hormones from the endoplasmic reticulum and modifies them before they are packaged into vesicles and transported to their final destinations.
- All of the above: The Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones. It is a crucial organelle in the secretory pathway of cells and plays a vital role in the processing, sorting, and packaging of various molecules.
In conclusion, the Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones, making option D, "All of the above," the correct answer.
Detailed Solution: Question 5
Answer:
In a cell, DNA is found in the nucleus, mitochondria, and plastids. Let's break down the options and see which one is correct.
A: Nucleus, mitochondria, and plastid
- Nucleus: The nucleus is often referred to as the control center of the cell. It contains the majority of the cell's DNA, organized into chromosomes.
- Mitochondria: Mitochondria are often referred to as the "powerhouses" of the cell. They have their own DNA, known as mitochondrial DNA (mtDNA), which is separate from the DNA found in the nucleus.
- Plastids: Plastids are found in plant cells and are involved in various functions such as photosynthesis. They also contain their own DNA, known as plastid DNA.
B: Nucleus, mitochondria, and Golgi body
- Golgi body: The Golgi body is involved in processing and packaging proteins. However, it does not contain DNA.
C: Mitochondria, Golgi body, and plastid
- This option is incorrect as it does not include the nucleus, which is where the majority of the cell's DNA is found.
D: Nucleus, Golgi body, and plastid
- This option is incorrect as it does not include mitochondria, which have their own DNA.
Therefore, the correct answer is A: Nucleus, mitochondria, and plastid, as DNA is found in all three of these cellular components.
In a cell, DNA is found in the nucleus, mitochondria, and plastids. Let's break down the options and see which one is correct.
A: Nucleus, mitochondria, and plastid
- Nucleus: The nucleus is often referred to as the control center of the cell. It contains the majority of the cell's DNA, organized into chromosomes.
- Mitochondria: Mitochondria are often referred to as the "powerhouses" of the cell. They have their own DNA, known as mitochondrial DNA (mtDNA), which is separate from the DNA found in the nucleus.
- Plastids: Plastids are found in plant cells and are involved in various functions such as photosynthesis. They also contain their own DNA, known as plastid DNA.
B: Nucleus, mitochondria, and Golgi body
- Golgi body: The Golgi body is involved in processing and packaging proteins. However, it does not contain DNA.
C: Mitochondria, Golgi body, and plastid
- This option is incorrect as it does not include the nucleus, which is where the majority of the cell's DNA is found.
D: Nucleus, Golgi body, and plastid
- This option is incorrect as it does not include mitochondria, which have their own DNA.
Therefore, the correct answer is A: Nucleus, mitochondria, and plastid, as DNA is found in all three of these cellular components.
Test: Diversity in Living Organisms- 2 - Question 6
Cartilage matrix is digested during its osteogenesis through :-
Detailed Solution: Question 6
Cartilage matrix digestion during osteogenesis:
During the process of osteogenesis, the cartilage matrix is digested through extracellular lysosomal activity. This process helps in the formation of bone tissue. Here is a detailed explanation:
1. Cartilage matrix:
- The cartilage matrix is composed of collagen fibers and proteoglycans.
- It provides structural support and cushioning to the developing bones.
2. Osteogenesis:
- Osteogenesis is the process of bone formation.
- It involves the gradual replacement of cartilage with bone tissue.
3. Extracellular lysosomal activity:
- Extracellular lysosomal activity refers to the breakdown of the cartilage matrix by lysosomes located outside the cells.
- Lysosomes are specialized organelles that contain enzymes capable of digesting various biological molecules.
4. Mechanism:
- Chondrocytes, the cells present in the cartilage matrix, undergo hypertrophy, which is an enlargement in size.
- Hypertrophic chondrocytes release enzymes, such as collagenases and proteases, into the extracellular space.
- These enzymes are then taken up by surrounding cells, such as osteoclasts, which are responsible for bone resorption.
- Osteoclasts secrete acid and enzymes, including lysosomal enzymes, to degrade the cartilage matrix.
- This breakdown of the cartilage matrix allows osteoblasts, the cells responsible for bone formation, to migrate and deposit new bone tissue.
5. Autophagy and heterophagy:
- Intracellular autophagic activity refers to the process by which cells recycle their own components, including organelles and proteins.
- Intracellular heterophagic activity refers to the process by which cells digest and eliminate extracellular material.
- While autophagy and heterophagy play important roles in cellular processes, they are not directly involved in the digestion of the cartilage matrix during osteogenesis.
6. Conclusion:
- The digestion of the cartilage matrix during osteogenesis primarily occurs through extracellular lysosomal activity.
- This process involves the release of enzymes by hypertrophic chondrocytes and their subsequent uptake by osteoclasts for the breakdown of the cartilage matrix.
- Autophagy and heterophagy, on the other hand, play different roles in cellular processes but are not directly involved in the digestion of the cartilage matrix during osteogenesis.
During the process of osteogenesis, the cartilage matrix is digested through extracellular lysosomal activity. This process helps in the formation of bone tissue. Here is a detailed explanation:
1. Cartilage matrix:
- The cartilage matrix is composed of collagen fibers and proteoglycans.
- It provides structural support and cushioning to the developing bones.
2. Osteogenesis:
- Osteogenesis is the process of bone formation.
- It involves the gradual replacement of cartilage with bone tissue.
3. Extracellular lysosomal activity:
- Extracellular lysosomal activity refers to the breakdown of the cartilage matrix by lysosomes located outside the cells.
- Lysosomes are specialized organelles that contain enzymes capable of digesting various biological molecules.
4. Mechanism:
- Chondrocytes, the cells present in the cartilage matrix, undergo hypertrophy, which is an enlargement in size.
- Hypertrophic chondrocytes release enzymes, such as collagenases and proteases, into the extracellular space.
- These enzymes are then taken up by surrounding cells, such as osteoclasts, which are responsible for bone resorption.
- Osteoclasts secrete acid and enzymes, including lysosomal enzymes, to degrade the cartilage matrix.
- This breakdown of the cartilage matrix allows osteoblasts, the cells responsible for bone formation, to migrate and deposit new bone tissue.
5. Autophagy and heterophagy:
- Intracellular autophagic activity refers to the process by which cells recycle their own components, including organelles and proteins.
- Intracellular heterophagic activity refers to the process by which cells digest and eliminate extracellular material.
- While autophagy and heterophagy play important roles in cellular processes, they are not directly involved in the digestion of the cartilage matrix during osteogenesis.
6. Conclusion:
- The digestion of the cartilage matrix during osteogenesis primarily occurs through extracellular lysosomal activity.
- This process involves the release of enzymes by hypertrophic chondrocytes and their subsequent uptake by osteoclasts for the breakdown of the cartilage matrix.
- Autophagy and heterophagy, on the other hand, play different roles in cellular processes but are not directly involved in the digestion of the cartilage matrix during osteogenesis.
Detailed Solution: Question 7
Lysosomal activity:
Lysosomes are membrane-bound organelles found in animal cells that contain enzymes responsible for breaking down various substances. Lysosomal activity refers to the processes and functions carried out by lysosomes in the cell.
Functions of lysosomal activity:
1. Reabsorption of tadpole tail: During metamorphosis, tadpoles undergo a process called tail resorption, where their tails are reabsorbed into their bodies. Lysosomes play a crucial role in this process by breaking down and recycling the tail tissues.
2. Mobilisation of stored substances: Lysosomes are involved in the degradation and recycling of cellular components and macromolecules. They break down stored substances, such as glycogen, lipids, and proteins, into smaller molecules that can be utilized by the cell for energy or other metabolic processes.
3. Removal of obstructions: Lysosomes also play a role in the removal of obstructions within the cell. They can engulf and break down foreign particles, cellular debris, or damaged organelles, helping to maintain cellular homeostasis.
Conclusion:
Lysosomal activity encompasses various important functions in the cell, including reabsorption of tadpole tail, mobilization of stored substances, and removal of obstructions. These processes are vital for the proper functioning and survival of the cell.
Lysosomes are membrane-bound organelles found in animal cells that contain enzymes responsible for breaking down various substances. Lysosomal activity refers to the processes and functions carried out by lysosomes in the cell.
Functions of lysosomal activity:
1. Reabsorption of tadpole tail: During metamorphosis, tadpoles undergo a process called tail resorption, where their tails are reabsorbed into their bodies. Lysosomes play a crucial role in this process by breaking down and recycling the tail tissues.
2. Mobilisation of stored substances: Lysosomes are involved in the degradation and recycling of cellular components and macromolecules. They break down stored substances, such as glycogen, lipids, and proteins, into smaller molecules that can be utilized by the cell for energy or other metabolic processes.
3. Removal of obstructions: Lysosomes also play a role in the removal of obstructions within the cell. They can engulf and break down foreign particles, cellular debris, or damaged organelles, helping to maintain cellular homeostasis.
Conclusion:
Lysosomal activity encompasses various important functions in the cell, including reabsorption of tadpole tail, mobilization of stored substances, and removal of obstructions. These processes are vital for the proper functioning and survival of the cell.
Detailed Solution: Question 8
When are lysosomes extra-active:
Therefore, the correct answer is b. Seed germination, as this is the stage where lysosomes are most extra-active.
- Seed germination: Lysosomes are extra-active during seed germination. This is the process where a seed develops into a new plant. During germination, lysosomes play a crucial role in breaking down stored nutrients in the seed, such as proteins, lipids, and carbohydrates, into smaller molecules that can be used by the growing plant.
- Seed maturation: Lysosomes are also active during seed maturation. This is the process where seeds reach their full size and develop the ability to withstand adverse conditions until they are ready to germinate. Lysosomes are involved in the degradation of cellular components and the recycling of nutrients during seed maturation.
- Flowering: Lysosomes are not particularly extra-active during the flowering stage. Flowering is primarily associated with processes such as pollination, fertilization, and seed production, where other cellular mechanisms play more significant roles.
- Fruiting: Lysosomes are not specifically extra-active during fruiting either. Fruiting is the stage where the ovary of a flower develops into a fruit containing seeds. While lysosomes may play a role in the breakdown of cellular components during fruit ripening, they are not significantly more active during this stage compared to seed germination or maturation.
Therefore, the correct answer is b. Seed germination, as this is the stage where lysosomes are most extra-active.
Detailed Solution: Question 9
Mitochondrion in Animal Cell
Mitochondria are important organelles found in animal cells. They play a crucial role in energy production and metabolism. Here is a detailed explanation:
1. Introduction:
Mitochondria are double-membraned organelles found in the cytoplasm of eukaryotic cells. They are often referred to as the "powerhouses" of the cell due to their role in generating energy.
2. Structure:
- Mitochondria have an outer membrane and an inner membrane, which are separated by an intermembrane space.
- The inner membrane has numerous folds called cristae, which increase the surface area for chemical reactions.
- Inside the inner membrane is the mitochondrial matrix, which contains enzymes involved in cellular respiration.
3. Function:
- ATP Production: Mitochondria are responsible for generating adenosine triphosphate (ATP), the main energy currency of the cell, through a process called oxidative phosphorylation.
- Cellular Respiration: They are involved in the breakdown of organic molecules, such as glucose, to produce ATP via aerobic respiration.
- Metabolism: Mitochondria are involved in various metabolic pathways, including the synthesis of amino acids, fatty acids, and nucleotides.
4. Abundance:
- Mitochondria are present in varying numbers depending on the cell type and its energy requirements.
- In general, mitochondria are more abundant in cells that require a high amount of energy, such as muscle cells.
5. Size:
- Mitochondria vary in size, but they are typically larger than most other organelles in the cell.
- However, they are not the largest organelle in the animal cell.
6. Conclusion:
In conclusion, mitochondria are crucial organelles in animal cells that perform various functions related to energy production and metabolism. While they are not the largest organelle, they are larger than most others.
Mitochondria are important organelles found in animal cells. They play a crucial role in energy production and metabolism. Here is a detailed explanation:
1. Introduction:
Mitochondria are double-membraned organelles found in the cytoplasm of eukaryotic cells. They are often referred to as the "powerhouses" of the cell due to their role in generating energy.
2. Structure:
- Mitochondria have an outer membrane and an inner membrane, which are separated by an intermembrane space.
- The inner membrane has numerous folds called cristae, which increase the surface area for chemical reactions.
- Inside the inner membrane is the mitochondrial matrix, which contains enzymes involved in cellular respiration.
3. Function:
- ATP Production: Mitochondria are responsible for generating adenosine triphosphate (ATP), the main energy currency of the cell, through a process called oxidative phosphorylation.
- Cellular Respiration: They are involved in the breakdown of organic molecules, such as glucose, to produce ATP via aerobic respiration.
- Metabolism: Mitochondria are involved in various metabolic pathways, including the synthesis of amino acids, fatty acids, and nucleotides.
4. Abundance:
- Mitochondria are present in varying numbers depending on the cell type and its energy requirements.
- In general, mitochondria are more abundant in cells that require a high amount of energy, such as muscle cells.
5. Size:
- Mitochondria vary in size, but they are typically larger than most other organelles in the cell.
- However, they are not the largest organelle in the animal cell.
6. Conclusion:
In conclusion, mitochondria are crucial organelles in animal cells that perform various functions related to energy production and metabolism. While they are not the largest organelle, they are larger than most others.
Test: Diversity in Living Organisms- 2 - Question 10
Outer mitochondrial membrane resembles bacterial membrane and outer chloroplast membrane in having :-
Detailed Solution: Question 10
Outer mitochondrial membrane resembles bacterial membrane and outer chloroplast membrane in having:
- Selective permeability: The outer mitochondrial membrane, bacterial membrane, and outer chloroplast membrane are all selectively permeable, meaning they allow certain molecules to pass through while restricting the passage of others. This selective permeability is crucial for maintaining the proper balance of ions and molecules within the organelles.
- Porin: Porins are protein channels found in the outer mitochondrial membrane, bacterial membrane, and outer chloroplast membrane. These channels allow the passage of small molecules, such as ions and metabolites, across the membrane. Porins play a role in the transport of essential molecules into and out of the organelles.
- Single ion channels: While the outer mitochondrial membrane and bacterial membrane may have single ion channels, the outer chloroplast membrane does not. Single ion channels are specialized protein channels that allow the selective transport of specific ions, such as potassium or calcium, across the membrane. These channels are essential for maintaining ion gradients and facilitating various cellular processes.
Therefore, the correct answer is A: Selective permeability.
- Selective permeability: The outer mitochondrial membrane, bacterial membrane, and outer chloroplast membrane are all selectively permeable, meaning they allow certain molecules to pass through while restricting the passage of others. This selective permeability is crucial for maintaining the proper balance of ions and molecules within the organelles.
- Porin: Porins are protein channels found in the outer mitochondrial membrane, bacterial membrane, and outer chloroplast membrane. These channels allow the passage of small molecules, such as ions and metabolites, across the membrane. Porins play a role in the transport of essential molecules into and out of the organelles.
- Single ion channels: While the outer mitochondrial membrane and bacterial membrane may have single ion channels, the outer chloroplast membrane does not. Single ion channels are specialized protein channels that allow the selective transport of specific ions, such as potassium or calcium, across the membrane. These channels are essential for maintaining ion gradients and facilitating various cellular processes.
Therefore, the correct answer is A: Selective permeability.
Test: Diversity in Living Organisms- 2 - Question 11
Chromoplasts are formed from chloroplasts during :-
Detailed Solution: Question 11
Chromoplasts are formed from chloroplasts during ripening of Tomato and Chilli
During the process of ripening, chloroplasts in certain fruits and vegetables undergo structural and functional changes, leading to the formation of chromoplasts. Chromoplasts are specialized plastids that are responsible for the synthesis and accumulation of pigments, primarily carotenoids, which give fruits and vegetables their characteristic colors.
Chloroplasts to Chromoplasts conversion occurs in the following fruits and vegetables:
1. Tomato: During the ripening of tomatoes, chloroplasts present in the green fruit start converting into chromoplasts. This conversion is accompanied by the breakdown of chlorophyll and the synthesis and accumulation of carotenoid pigments, such as lycopene, which gives tomatoes their red color.
2. Chilli: Similar to tomatoes, the ripening of chilli peppers involves the transformation of chloroplasts into chromoplasts. The green chilli peppers turn into vibrant red or yellow colors as the chlorophyll breaks down and carotenoid pigments, such as capsanthin and capsorubin, are synthesized and accumulated in the chromoplasts.
In summary, chromoplasts are formed from chloroplasts during the ripening of tomatoes and chilli peppers. This conversion is essential for the development of vibrant colors in these fruits and vegetables, making them visually appealing and attractive to consumers.
During the process of ripening, chloroplasts in certain fruits and vegetables undergo structural and functional changes, leading to the formation of chromoplasts. Chromoplasts are specialized plastids that are responsible for the synthesis and accumulation of pigments, primarily carotenoids, which give fruits and vegetables their characteristic colors.
Chloroplasts to Chromoplasts conversion occurs in the following fruits and vegetables:
1. Tomato: During the ripening of tomatoes, chloroplasts present in the green fruit start converting into chromoplasts. This conversion is accompanied by the breakdown of chlorophyll and the synthesis and accumulation of carotenoid pigments, such as lycopene, which gives tomatoes their red color.
2. Chilli: Similar to tomatoes, the ripening of chilli peppers involves the transformation of chloroplasts into chromoplasts. The green chilli peppers turn into vibrant red or yellow colors as the chlorophyll breaks down and carotenoid pigments, such as capsanthin and capsorubin, are synthesized and accumulated in the chromoplasts.
In summary, chromoplasts are formed from chloroplasts during the ripening of tomatoes and chilli peppers. This conversion is essential for the development of vibrant colors in these fruits and vegetables, making them visually appealing and attractive to consumers.
Test: Diversity in Living Organisms- 2 - Question 12
Experiments on Acetabularia by Hammerling proved the role of :-
Detailed Solution: Question 12
Experiments on Acetabularia by Hammerling:
Hammerling conducted experiments on the single-celled green alga Acetabularia, which has a large, visible nucleus. These experiments helped to determine the role of the nucleus in heredity.
Key Findings:
1. Regeneration of Acetabularia: Hammerling observed that when the cap of an Acetabularia cell is removed, it can regenerate a new cap. This regeneration occurs even when the nucleus is removed from the original cell and replaced with a nucleus from a different species of Acetabularia.
2. Nucleus Determines Cap Formation: The regenerated cap of Acetabularia always resembled the species of the nucleus used, rather than the species of the cytoplasm. This indicated that the nucleus has a significant role in determining the developmental characteristics of the cap.
3. Role of Cytoplasm: Hammerling also observed that the cytoplasm of the Acetabularia cell did not influence the developmental characteristics of the cap. Even when the cytoplasm was replaced with cytoplasm from a different species, the regenerated cap still resembled the species of the nucleus.
4. Importance of Nucleoplasmic Ratio: Hammerling further investigated the role of the nucleus by conducting experiments where he manipulated the nucleoplasmic ratio. He found that when the nucleus was transplanted into a smaller cytoplasmic volume, the regenerated cap was smaller, and vice versa. This indicated that the nucleoplasmic ratio plays a role in determining the size of the cap.
Conclusion:
Hammerling's experiments on Acetabularia provided evidence for the role of the nucleus in heredity and developmental characteristics. The nucleus was found to determine the cap formation, while the cytoplasm had little influence. The experiments also highlighted the importance of the nucleoplasmic ratio in determining the size of the cap. These findings contributed to our understanding of the role of the nucleus and its genetic material in controlling cellular development and heredity.
Hammerling conducted experiments on the single-celled green alga Acetabularia, which has a large, visible nucleus. These experiments helped to determine the role of the nucleus in heredity.
Key Findings:
1. Regeneration of Acetabularia: Hammerling observed that when the cap of an Acetabularia cell is removed, it can regenerate a new cap. This regeneration occurs even when the nucleus is removed from the original cell and replaced with a nucleus from a different species of Acetabularia.
2. Nucleus Determines Cap Formation: The regenerated cap of Acetabularia always resembled the species of the nucleus used, rather than the species of the cytoplasm. This indicated that the nucleus has a significant role in determining the developmental characteristics of the cap.
3. Role of Cytoplasm: Hammerling also observed that the cytoplasm of the Acetabularia cell did not influence the developmental characteristics of the cap. Even when the cytoplasm was replaced with cytoplasm from a different species, the regenerated cap still resembled the species of the nucleus.
4. Importance of Nucleoplasmic Ratio: Hammerling further investigated the role of the nucleus by conducting experiments where he manipulated the nucleoplasmic ratio. He found that when the nucleus was transplanted into a smaller cytoplasmic volume, the regenerated cap was smaller, and vice versa. This indicated that the nucleoplasmic ratio plays a role in determining the size of the cap.
Conclusion:
Hammerling's experiments on Acetabularia provided evidence for the role of the nucleus in heredity and developmental characteristics. The nucleus was found to determine the cap formation, while the cytoplasm had little influence. The experiments also highlighted the importance of the nucleoplasmic ratio in determining the size of the cap. These findings contributed to our understanding of the role of the nucleus and its genetic material in controlling cellular development and heredity.
Detailed Solution: Question 13
Plastids with irregular shape:
Plastids are organelles found in the cells of plants and algae. They are responsible for various functions such as photosynthesis, storage of pigments, and synthesis of starch. While most plastids have a regular shape, there are some plastids that have an irregular shape. These include:
1. Chromoplasts: Chromoplasts are plastids responsible for the synthesis and storage of pigments other than chlorophyll. They give fruits and flowers their vibrant colors. Unlike chloroplasts, which have a regular shape, chromoplasts can have an irregular shape depending on the type of pigment they contain.
2. Amyloplasts: Amyloplasts are plastids that store starch. They are commonly found in storage tissues such as roots, tubers, and seeds. Unlike chloroplasts, amyloplasts do not contain pigments and have an irregular shape.
Summary:
Plastids with irregular shapes include chromoplasts and amyloplasts. Chromoplasts are responsible for the synthesis and storage of pigments, giving fruits and flowers their colors. Amyloplasts, on the other hand, store starch and are commonly found in storage tissues.
Plastids are organelles found in the cells of plants and algae. They are responsible for various functions such as photosynthesis, storage of pigments, and synthesis of starch. While most plastids have a regular shape, there are some plastids that have an irregular shape. These include:
1. Chromoplasts: Chromoplasts are plastids responsible for the synthesis and storage of pigments other than chlorophyll. They give fruits and flowers their vibrant colors. Unlike chloroplasts, which have a regular shape, chromoplasts can have an irregular shape depending on the type of pigment they contain.
2. Amyloplasts: Amyloplasts are plastids that store starch. They are commonly found in storage tissues such as roots, tubers, and seeds. Unlike chloroplasts, amyloplasts do not contain pigments and have an irregular shape.
Summary:
Plastids with irregular shapes include chromoplasts and amyloplasts. Chromoplasts are responsible for the synthesis and storage of pigments, giving fruits and flowers their colors. Amyloplasts, on the other hand, store starch and are commonly found in storage tissues.
Detailed Solution: Question 14
Peroxisomes and Glyoxysomes: Microbodies
- Peroxisomes and glyoxysomes are both types of microbodies, which are specialized organelles found in eukaryotic cells.
- Microbodies are small, membrane-bound organelles that carry out specific metabolic functions.
- Both peroxisomes and glyoxysomes contain enzymes that are involved in various metabolic processes.
- Peroxisomes are primarily involved in the breakdown of fatty acids and the detoxification of harmful substances.
- Glyoxysomes, on the other hand, are found in plant cells and are involved in the conversion of stored lipids into carbohydrates during germination.
- Both organelles have a single membrane that separates their contents from the rest of the cell.
- Unlike other organelles, peroxisomes and glyoxysomes do not contain DNA and are not involved in protein synthesis.
- Although they are considered microbodies, peroxisomes and glyoxysomes are distinct from other types of microbodies, such as lysosomes and proteasomes.
- Overall, peroxisomes and glyoxysomes are important organelles involved in the metabolism and energy transformation processes within cells.
- Peroxisomes and glyoxysomes are both types of microbodies, which are specialized organelles found in eukaryotic cells.
- Microbodies are small, membrane-bound organelles that carry out specific metabolic functions.
- Both peroxisomes and glyoxysomes contain enzymes that are involved in various metabolic processes.
- Peroxisomes are primarily involved in the breakdown of fatty acids and the detoxification of harmful substances.
- Glyoxysomes, on the other hand, are found in plant cells and are involved in the conversion of stored lipids into carbohydrates during germination.
- Both organelles have a single membrane that separates their contents from the rest of the cell.
- Unlike other organelles, peroxisomes and glyoxysomes do not contain DNA and are not involved in protein synthesis.
- Although they are considered microbodies, peroxisomes and glyoxysomes are distinct from other types of microbodies, such as lysosomes and proteasomes.
- Overall, peroxisomes and glyoxysomes are important organelles involved in the metabolism and energy transformation processes within cells.
Test: Diversity in Living Organisms- 2 - Question 15
In which organism flame cells form the excretory system?
Detailed Solution: Question 15
A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms, rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.
Detailed Solution: Question 16
Microfilaments were discovered by Palevizetal.
The discovery of microfilaments in the field of cell biology is credited to the researchers Palevizetal. Here is a detailed explanation:
- Microfilaments: Microfilaments are one of the three major types of cytoskeletal filaments present in the cells. They are composed of actin protein and play a crucial role in cell structure, movement, and division.
- Discovery: The discovery of microfilaments occurred through scientific research and experimentation.
- Palevizetal: The specific researchers credited with the discovery of microfilaments are Palevizetal. The exact names of the researchers in the Palevizetal group are not mentioned in the given options.
- Other Researchers: It is important to note that other researchers have also contributed to the understanding of microfilaments. Some of the notable researchers in this field include Slautterback, Altman, Ledbetter, and Porter. However, in this specific question, the correct answer is Palevizetal.
To summarize, microfilaments were discovered by Palevizetal, a group of researchers who made significant contributions to the field of cell biology.
Detailed Solution: Question 17
Microfilaments are required for:
- Movement of flagella and cilia: Microfilaments, also known as actin filaments, are involved in the movement of flagella and cilia. They provide structural support and generate the force required for the beating motion of these cellular appendages.
- Cell polarity: Microfilaments play a crucial role in establishing and maintaining cell polarity. They help in the formation of polarized structures such as cell protrusions, such as filopodia and lamellipodia, which are involved in cell migration and tissue organization.
- Sol-gel changes: Microfilaments are involved in the dynamic changes between the sol and gel states of the cytoplasm. They contribute to the contractility and shape changes of the cell by regulating the assembly and disassembly of actin filaments.
Therefore, the correct answer is D: All the above. Microfilaments are essential for the movement of flagella and cilia, cell polarity, and sol-gel changes in the cytoplasm.
- Movement of flagella and cilia: Microfilaments, also known as actin filaments, are involved in the movement of flagella and cilia. They provide structural support and generate the force required for the beating motion of these cellular appendages.
- Cell polarity: Microfilaments play a crucial role in establishing and maintaining cell polarity. They help in the formation of polarized structures such as cell protrusions, such as filopodia and lamellipodia, which are involved in cell migration and tissue organization.
- Sol-gel changes: Microfilaments are involved in the dynamic changes between the sol and gel states of the cytoplasm. They contribute to the contractility and shape changes of the cell by regulating the assembly and disassembly of actin filaments.
Therefore, the correct answer is D: All the above. Microfilaments are essential for the movement of flagella and cilia, cell polarity, and sol-gel changes in the cytoplasm.
Detailed Solution: Question 18
Cell polarity is determined by microtubules.
Microtubules are one of the key components of the cytoskeleton, which plays a crucial role in maintaining cell structure and function. They are composed of tubulin protein subunits and form long hollow tubes within the cell.
Here is a detailed explanation of how microtubules contribute to cell polarity:
- Microtubule organization: Microtubules are organized in a polarized manner within the cell. They have a plus end and a minus end, with the plus end typically located towards the cell periphery and the minus end towards the center of the cell.
- Polarity establishment: During cell division, microtubules play a role in establishing cell polarity. They align along the axis of cell division and help position the mitotic spindle, which is necessary for proper chromosome segregation.
- Role in intracellular transport: Microtubules act as tracks for intracellular transport. Motor proteins, such as dynein and kinesin, move along microtubules to transport various cellular components, including organelles, vesicles, and proteins. This directional movement along microtubules contributes to cell polarity.
- Cell migration: Microtubules are involved in cell migration, which requires the establishment of front-rear polarity. They help in the formation of cellular protrusions called lamellipodia and filopodia, which are important for cell movement.
- Establishing cell shape: Microtubules provide structural support and help maintain cell shape. They form a network that helps distribute forces within the cell and regulate the positioning of other cellular structures.
- Signal transduction: Microtubules can also transmit signals from the cell surface to the nucleus. They interact with various signaling molecules and can influence gene expression and cellular responses.
In summary, microtubules play a crucial role in determining cell polarity by organizing themselves in a polarized manner, facilitating intracellular transport, contributing to cell migration and shape, and participating in signal transduction pathways.
Detailed Solution: Question 19
The nucleus is a small, dense and spherical structure present in the nucleus of the cell that is visible during the interphase of the cell division under the microscope.
The term Nucleolus was coined by Bowman but first described by Fontana in the year 1781.
So, the correct answer is Bowman.
Test: Diversity in Living Organisms- 2 - Question 20
Which of the following phenomena is commonly referred as 'cell drinking' ?
Detailed Solution: Question 20
Explanation:
The phenomenon commonly referred to as "cell drinking" is Pinocytosis.
Pinocytosis:
- Pinocytosis is a form of endocytosis, which is the process by which cells take in substances from their surrounding environment.
- In pinocytosis, the cell engulfs extracellular fluid and any dissolved solutes that may be present in it.
- The cell membrane forms a small invagination or pocket, which then pinches off to form a vesicle containing the engulfed fluid and solutes.
- This process allows cells to take in nutrients, such as sugars and proteins, as well as other molecules and ions present in the extracellular fluid.
Other options:
- Exocytosis: Exocytosis is the process by which cells release substances from their cytoplasm into the extracellular space.
- Endocytosis: Endocytosis is a general term that refers to the process by which cells take in substances from their environment, which includes pinocytosis and other forms of endocytosis.
- Phagocytosis: Phagocytosis is a specific form of endocytosis in which cells engulf large particles, such as bacteria or cellular debris.
Therefore, the correct answer is B: Pinocytosis.
The phenomenon commonly referred to as "cell drinking" is Pinocytosis.
Pinocytosis:
- Pinocytosis is a form of endocytosis, which is the process by which cells take in substances from their surrounding environment.
- In pinocytosis, the cell engulfs extracellular fluid and any dissolved solutes that may be present in it.
- The cell membrane forms a small invagination or pocket, which then pinches off to form a vesicle containing the engulfed fluid and solutes.
- This process allows cells to take in nutrients, such as sugars and proteins, as well as other molecules and ions present in the extracellular fluid.
Other options:
- Exocytosis: Exocytosis is the process by which cells release substances from their cytoplasm into the extracellular space.
- Endocytosis: Endocytosis is a general term that refers to the process by which cells take in substances from their environment, which includes pinocytosis and other forms of endocytosis.
- Phagocytosis: Phagocytosis is a specific form of endocytosis in which cells engulf large particles, such as bacteria or cellular debris.
Therefore, the correct answer is B: Pinocytosis.
Detailed Solution: Question 21
The two centrioles of a pair occur at right angles to each other.
The centrioles are organelles found in animal cells that play a crucial role in cell division. They are composed of microtubules and are involved in the formation of the spindle fibers during mitosis and meiosis. The two centrioles in a pair are positioned in a specific arrangement.
Here's a detailed explanation of the arrangement of the two centrioles:
1. Structure of a centriole:
- A centriole is cylindrical in shape and consists of nine microtubule triplets.
- Each triplet is composed of three microtubules arranged in a circular pattern.
- The triplets are connected to each other by interconnecting proteins.
2. Pairing of centrioles:
- Two centrioles come together to form a pair called a centrosome.
- The centrosome is located near the nucleus of the cell.
3. Orientation of centrioles:
- The two centrioles in a pair are oriented at right angles to each other.
- One centriole is perpendicular to the other, forming a T-shaped structure.
- The centriole that is perpendicular to the other is called the mother centriole, while the one parallel to it is called the daughter centriole.
4. Function of centrioles:
- The centrioles play a crucial role in cell division by organizing the microtubules into a spindle apparatus.
- The spindle fibers help in the separation of chromosomes during mitosis and meiosis.
In conclusion, the two centrioles of a pair occur at right angles to each other, forming a T-shaped structure. This arrangement is essential for their function in cell division.
The centrioles are organelles found in animal cells that play a crucial role in cell division. They are composed of microtubules and are involved in the formation of the spindle fibers during mitosis and meiosis. The two centrioles in a pair are positioned in a specific arrangement.
Here's a detailed explanation of the arrangement of the two centrioles:
1. Structure of a centriole:
- A centriole is cylindrical in shape and consists of nine microtubule triplets.
- Each triplet is composed of three microtubules arranged in a circular pattern.
- The triplets are connected to each other by interconnecting proteins.
2. Pairing of centrioles:
- Two centrioles come together to form a pair called a centrosome.
- The centrosome is located near the nucleus of the cell.
3. Orientation of centrioles:
- The two centrioles in a pair are oriented at right angles to each other.
- One centriole is perpendicular to the other, forming a T-shaped structure.
- The centriole that is perpendicular to the other is called the mother centriole, while the one parallel to it is called the daughter centriole.
4. Function of centrioles:
- The centrioles play a crucial role in cell division by organizing the microtubules into a spindle apparatus.
- The spindle fibers help in the separation of chromosomes during mitosis and meiosis.
In conclusion, the two centrioles of a pair occur at right angles to each other, forming a T-shaped structure. This arrangement is essential for their function in cell division.
Test: Diversity in Living Organisms- 2 - Question 22
Cell organelle having a cartwheel constitution is :-
Detailed Solution: Question 22
Cell organelle having a cartwheel constitution is:
The correct answer is option A: Centriole and basal body.
Explanation:
Centrioles and basal bodies are cell organelles that have a cartwheel constitution. These structures play important roles in cell division and organization. Here is a detailed explanation of these organelles:
1. Centriole:
- Centrioles are cylindrical structures found in animal cells, usually present in pairs near the nucleus.
- They are composed of microtubules arranged in a cartwheel-like pattern.
- Centrioles are involved in the formation of the spindle fibers during cell division, which help separate the chromosomes.
- They also play a role in the organization of the cytoskeleton and the positioning of various organelles within the cell.
2. Basal Body:
- Basal bodies are similar in structure to centrioles and are found in eukaryotic cells.
- They are located at the base of cilia and flagella, serving as the anchor point for these structures.
- Basal bodies also have a cartwheel-like arrangement of microtubules.
- They are involved in the assembly and organization of cilia and flagella, which are important for cell motility and sensory functions.
In conclusion, centrioles and basal bodies are cell organelles that have a cartwheel constitution. They play crucial roles in cell division, cytoskeleton organization, and cell motility.
The correct answer is option A: Centriole and basal body.
Explanation:
Centrioles and basal bodies are cell organelles that have a cartwheel constitution. These structures play important roles in cell division and organization. Here is a detailed explanation of these organelles:
1. Centriole:
- Centrioles are cylindrical structures found in animal cells, usually present in pairs near the nucleus.
- They are composed of microtubules arranged in a cartwheel-like pattern.
- Centrioles are involved in the formation of the spindle fibers during cell division, which help separate the chromosomes.
- They also play a role in the organization of the cytoskeleton and the positioning of various organelles within the cell.
2. Basal Body:
- Basal bodies are similar in structure to centrioles and are found in eukaryotic cells.
- They are located at the base of cilia and flagella, serving as the anchor point for these structures.
- Basal bodies also have a cartwheel-like arrangement of microtubules.
- They are involved in the assembly and organization of cilia and flagella, which are important for cell motility and sensory functions.
In conclusion, centrioles and basal bodies are cell organelles that have a cartwheel constitution. They play crucial roles in cell division, cytoskeleton organization, and cell motility.
Detailed Solution: Question 23
Flagellum beats:
- Flagella are whip-like structures that are used by many microorganisms for locomotion. The beating of flagella allows these organisms to move through their environment.
- The flagellum beats in a specific pattern to create movement. This beating pattern is characterized by the following factors:
Independently:
- Each flagellum beats independently of other flagella on the organism.
- This means that each flagellum can move in a different direction or at a different speed, allowing for more precise movement.
Undulatory:
- The flagellum moves in an undulating or wave-like motion.
- This motion allows the flagellum to create a propulsive force that pushes the organism forward.
Symmetrically:
- The flagellum beats in a symmetrical manner.
- This means that the motion of the flagellum is the same on both sides, creating a balanced and efficient movement.
Therefore, the correct answer is B: Independently, undulatory, and symmetrically.
- Flagella are whip-like structures that are used by many microorganisms for locomotion. The beating of flagella allows these organisms to move through their environment.
- The flagellum beats in a specific pattern to create movement. This beating pattern is characterized by the following factors:
Independently:
- Each flagellum beats independently of other flagella on the organism.
- This means that each flagellum can move in a different direction or at a different speed, allowing for more precise movement.
Undulatory:
- The flagellum moves in an undulating or wave-like motion.
- This motion allows the flagellum to create a propulsive force that pushes the organism forward.
Symmetrically:
- The flagellum beats in a symmetrical manner.
- This means that the motion of the flagellum is the same on both sides, creating a balanced and efficient movement.
Therefore, the correct answer is B: Independently, undulatory, and symmetrically.
Detailed Solution: Question 24
Food vacuole formation:
The formation of a food vacuole occurs through a process called phagocytosis, which involves the engulfment and digestion of food particles by a cell. The food vacuole is responsible for storing and digesting the ingested food.
The steps involved in the formation of a food vacuole are:
1. Phagocytosis: The process begins with the engulfment of food particles by the cell. This is done through the formation of a phagosome, which is a membrane-bound vesicle that encloses the ingested food.
2. Lysosome fusion: The phagosome then fuses with a lysosome, which is an organelle containing digestive enzymes. This fusion leads to the formation of a phagolysosome, where the food particles are exposed to the digestive enzymes.
3. Digestion: Within the phagolysosome, the digestive enzymes break down the food particles into simpler molecules that can be absorbed and used by the cell. This process is known as intracellular digestion.
4. Absorption: The digested food molecules are then absorbed into the cytoplasm of the cell for further processing and utilization.
5. Food vacuole formation: As the digestion and absorption process continues, the phagolysosome gradually matures into a food vacuole. The food vacuole is a specialized compartment within the cell that holds the digested food until it is fully utilized or expelled from the cell.
In conclusion, the formation of a food vacuole involves the processes of phagocytosis, lysosome fusion, digestion, absorption, and maturation of the phagolysosome into a food vacuole. The correct answer is B: Phagosome + Lysosome.
The formation of a food vacuole occurs through a process called phagocytosis, which involves the engulfment and digestion of food particles by a cell. The food vacuole is responsible for storing and digesting the ingested food.
The steps involved in the formation of a food vacuole are:
1. Phagocytosis: The process begins with the engulfment of food particles by the cell. This is done through the formation of a phagosome, which is a membrane-bound vesicle that encloses the ingested food.
2. Lysosome fusion: The phagosome then fuses with a lysosome, which is an organelle containing digestive enzymes. This fusion leads to the formation of a phagolysosome, where the food particles are exposed to the digestive enzymes.
3. Digestion: Within the phagolysosome, the digestive enzymes break down the food particles into simpler molecules that can be absorbed and used by the cell. This process is known as intracellular digestion.
4. Absorption: The digested food molecules are then absorbed into the cytoplasm of the cell for further processing and utilization.
5. Food vacuole formation: As the digestion and absorption process continues, the phagolysosome gradually matures into a food vacuole. The food vacuole is a specialized compartment within the cell that holds the digested food until it is fully utilized or expelled from the cell.
In conclusion, the formation of a food vacuole involves the processes of phagocytosis, lysosome fusion, digestion, absorption, and maturation of the phagolysosome into a food vacuole. The correct answer is B: Phagosome + Lysosome.
Test: Diversity in Living Organisms- 2 - Question 25
Chromatin material which remains condensed during interphase is called:-
Detailed Solution: Question 25
Condensed Chromatin Material During Interphase
Characteristics of Heterochromatin:
Functions of Heterochromatin:
In conclusion, heterochromatin is the condensed chromatin material that remains during interphase. It has distinct characteristics and functions that contribute to the overall organization and regulation of the genome.
During interphase, the cell undergoes various activities such as growth, DNA replication, and preparation for cell division. The chromatin, which is the combination of DNA and proteins, is usually relaxed and dispersed throughout the nucleus. However, there is a fraction of chromatin material that remains condensed and tightly packed. This condensed chromatin is called heterochromatin.
Characteristics of Heterochromatin:
- Condensed Structure: Heterochromatin appears as dark-stained regions under a microscope due to its highly condensed structure.
- Transcriptionally Inactive: Heterochromatin is usually transcriptionally inactive, meaning that the genes within this region are not actively transcribed or expressed.
- Highly Repetitive DNA: Heterochromatin contains highly repetitive DNA sequences, such as satellite DNA and transposable elements.
- Stable Structure: Heterochromatin remains condensed throughout the cell cycle, including interphase.
Functions of Heterochromatin:
- Maintenance of Chromosome Integrity: Heterochromatin plays a crucial role in maintaining the structure and stability of chromosomes.
- Gene Regulation: The condensed nature of heterochromatin prevents the access of transcription factors and other regulatory proteins, leading to gene silencing.
- Centromere and Telomere Function: Heterochromatin is found at centromeres and telomeres, which are essential for proper chromosome segregation and chromosome end protection, respectively.
- Preservation of Chromosomal Architecture: Heterochromatin helps in organizing and compacting chromosomes within the nucleus, ensuring their proper spatial arrangement.
In conclusion, heterochromatin is the condensed chromatin material that remains during interphase. It has distinct characteristics and functions that contribute to the overall organization and regulation of the genome.
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