Olympiad Test: Cell - Structure And Functions - 2 - Class 8 MCQ

Organelles responsible for energy production in a cell:
- Mitochondria: Mitochondria are known as the powerhouses of the cell. They are double-membraned organelles that generate energy in the form of ATP (adenosine triphosphate) through cellular respiration.
Other organelles:
- Vacuoles: Vacuoles are responsible for storage and transportation of various substances within the cell. While they do not directly produce energy, they may store nutrients or pigments that can be used for energy production.
- Chloroplasts: Chloroplasts are found in plant cells and are responsible for photosynthesis. They convert light energy into chemical energy (glucose) using chlorophyll and other pigments.
- Golgi bodies: Golgi bodies are involved in the modification, packaging, and distribution of proteins and lipids. They do not directly produce energy in the cell.
Conclusion:
In summary, the main organelle responsible for energy production in a cell is the mitochondria. While vacuoles, chloroplasts, and golgi bodies have other important functions in the cell, they are not primarily involved in energy production.

The jelly-like substance found in a cell is called cytoplasm.
The cytoplasm is a semi-fluid substance that fills the space between the cell membrane and the nucleus. It is present in all types of cells, both prokaryotic and eukaryotic. Here are some key points about cytoplasm:
- Definition: Cytoplasm is the region of the cell that contains various organelles, cytosol (the liquid component), and various molecules necessary for cellular processes.
- Composition: It is primarily composed of water, ions, proteins, lipids, carbohydrates, and other organic and inorganic molecules.
- Functions: Cytoplasm serves several important functions in the cell, including:
1. Support and Protection: It provides structural support to the cell organelles and helps maintain their shape. The cytoplasm also acts as a cushion, protecting the organelles from mechanical damage.
2. Cellular Metabolism: Many metabolic reactions occur in the cytoplasm. It provides a site for various biochemical processes, such as glycolysis, protein synthesis, and lipid metabolism.
3. Transport: Cytoplasm facilitates the movement of molecules and organelles within the cell. It contains a network of protein filaments called the cytoskeleton, which helps in intracellular transport.
4. Storage: Cytoplasm can store various substances, such as nutrients, ions, and waste products, until they are needed or can be eliminated.
In conclusion, cytoplasm is a vital component of the cell and plays a crucial role in supporting cellular processes, metabolism, and transport. It is the jelly-like substance that fills the space between the cell membrane and the nucleus.

The substance used to stain the cheek cells of human beings to observe them clearly under a microscope is ink.
To understand why ink is used as a stain for observing cheek cells, let's look at the properties and functions of stains in microscopy:
1. Purpose of Staining:
Staining is a common technique in microscopy used to enhance the visibility of cells or cellular components. It helps to differentiate between cellular structures and highlight specific features.
2. Types of Stains:
There are various types of stains available, including basic dyes, acidic dyes, and differential stains. Basic dyes, such as crystal violet, methylene blue, and safranin, are commonly used for staining cheek cells.
3. Properties of Ink:
Ink is a type of dye or pigment that is commonly used in writing and printing. It contains various chemical compounds that provide color. While different types of ink may have different compositions, they are generally water-based and contain dyes or pigments that can bind to cell structures.
4. Staining Cheek Cells:
When observing cheek cells under a microscope, staining with ink helps to make the cells more visible and distinguishable. The ink binds to the cellular components, such as the nucleus and cytoplasm, providing contrast and allowing for better observation and analysis.
5. Other Options:
While ink is commonly used, other stains like methylene blue or eosin can also be used to stain cheek cells. However, the question specifically mentions ink as the answer, indicating that it is the most appropriate choice.
In conclusion, ink is the substance commonly used to stain cheek cells of human beings to observe them clearly under a microscope. It helps enhance visibility and allows for better analysis of cellular structures.

The cytoplasm and the nucleus together make up the protoplasm. The protoplasm refers to the living content of a cell, which includes everything inside the cell membrane except for the cell wall in plant cells. Here is a detailed explanation:
1. Cytoplasm:
- The cytoplasm is a jelly-like substance present inside the cell membrane.
- It fills the space between the cell membrane and the nucleus.
- It is composed of water, salts, organic molecules, and various organelles.
- Many cellular processes, such as metabolism and protein synthesis, occur in the cytoplasm.
- It also provides support and structure to the cell.
2. Nucleus:
- The nucleus is the control center of the cell.
- It is a membrane-bound organelle that contains the cell's genetic material, DNA.
- The DNA in the nucleus carries the instructions for the cell's functioning and determines its characteristics.
- It is surrounded by a nuclear membrane and contains a nucleolus.
- The nucleus regulates gene expression and plays a crucial role in cell division.
3. Protoplasm:
- Protoplasm refers to the living content of a cell, including the cytoplasm and the nucleus.
- It encompasses all the cellular structures and substances necessary for the cell's survival and functioning.
- The protoplasm is responsible for various cellular activities, such as metabolism, growth, and reproduction.
Therefore, option B: protoplasm is the correct answer as it represents the combination of the cytoplasm and the nucleus in a cell.

Answer:
The spiral band in the spirogyra cell is the chloroplast. Here is a detailed explanation:
What is Spirogyra?
Spirogyra is a filamentous green algae commonly found in freshwater environments. It is made up of cylindrical cells arranged end-to-end in a long filament.
Structure of Spirogyra Cell
The spirogyra cell has various structures, including the nucleus, cytoplasm, mitochondria, and chloroplasts. Among these structures, the spiral band is specifically related to the chloroplast.
What is the Chloroplast?
Chloroplasts are organelles found in plant cells and some algae. They are responsible for photosynthesis, the process by which plants convert sunlight into energy. Chloroplasts contain chlorophyll, the pigment that gives plants their green color and allows them to absorb light energy.
The Spiral Band
The spiral band in the spirogyra cell refers to the arrangement of chloroplasts. These chloroplasts are elongated and spiral-shaped, forming a band within the cell.
Significance of the Spiral Band
The spiral band arrangement of chloroplasts in spirogyra cells allows for efficient light absorption during photosynthesis. The spiral shape increases the surface area of the chloroplasts, maximizing their exposure to sunlight. This optimizes the production of energy-rich molecules, such as glucose, which the cell can use for growth and other metabolic processes.
In conclusion, the spiral band in the spirogyra cell is the chloroplast, which plays a crucial role in photosynthesis and energy production.

Explanation:
The correct answer is B: All cells are identical in shape and size.
The cell theory is a fundamental concept in biology that describes the basic properties of cells. It was proposed by Matthias Schleiden and Theodor Schwann in the 19th century. The cell theory consists of three main principles:
1. Cells are the basic structural units of a living organism: This principle asserts that all living organisms are composed of cells, which are the building blocks of life.
2. New cells are formed due to division in existing cells: This principle states that cells can only arise from pre-existing cells through cell division. This process ensures the continuity of life and the growth and development of organisms.
3. The way an organism functions depends on the way the cells work: This principle emphasizes the importance of cells in the functioning of organisms. The activities and functions of an organism are carried out by its cells, which perform specific tasks necessary for the survival and maintenance of life.
However, the cell theory does not assert that all cells are identical in shape and size. In reality, cells can vary greatly in shape, size, and function depending on their specialized roles in the organism. Different types of cells have different structures and functions that enable them to perform specific tasks in the body.
In conclusion, the correct answer is B: All cells are identical in shape and size. This statement is not supported by the cell theory, as cells can vary in shape and size depending on their specialized functions.

The cell with cytoplasm in it is a parenchyma cell.
Explanation:
Parenchyma cells are the most common type of plant cells and are found in various parts of the plant, including the leaves, stems, and roots. These cells are involved in various functions, such as photosynthesis, storage, and secretion.
Here is a detailed explanation of why the correct answer is parenchyma:
- Parenchyma cells:
- Parenchyma cells are living cells that have a large central vacuole surrounded by a thin layer of cytoplasm.
- They have a primary cell wall made up of cellulose and pectin.
- These cells are usually isodiametric in shape, meaning they have similar dimensions in all directions.
- Parenchyma cells are capable of dividing and differentiating into other cell types if needed.
- They have various functions, such as providing support, storing nutrients, and participating in photosynthesis.
- Examples of parenchyma cells include the palisade parenchyma in leaves and the cortex parenchyma in stems and roots.
- Sclerid cells:
- Sclerid cells are a type of sclerenchyma cell that provides mechanical support to the plant.
- They have a thick secondary cell wall with lignin, making them rigid and hard.
- Sclerid cells are usually dead at maturity and have no cytoplasm.
- They are found in hard tissues like the seed coat and nutshells.

- Sclerenchyma cells:
- Sclerenchyma cells are specialized plant cells that provide mechanical support to the plant.
- They have thick secondary cell walls with lignin, which makes them rigid and strong.
- Sclerenchyma cells are usually dead at maturity and have no cytoplasm.
- They are found in parts of the plant that require structural support, such as the stems, roots, and vascular tissues.
- Cork cells:
- Cork cells, also known as phellem cells, are a type of protective tissue found in the outer bark of woody plants.
- They are dead at maturity and have no cytoplasm.
- Cork cells have a thick secondary cell wall containing suberin, which makes them impermeable to water and gases.
- Their main function is to protect the underlying tissues from mechanical damage, water loss, and pathogens.
Based on the descriptions above, it is clear that the cell with cytoplasm in it is a parenchyma cell. Parenchyma cells are living cells with a large central vacuole surrounded by a thin layer of cytoplasm, whereas sclerid cells, sclerenchyma cells, and cork cells are all dead at maturity and do not contain cytoplasm.

Single Cell Performing All Life Functions
In the given options, a single cell does not perform all life functions in the case of the mosquito. Here's a detailed explanation:
Amoeba:
- Amoeba is a single-celled organism belonging to the group of protozoans.
- It can carry out all life functions like respiration, digestion, excretion, reproduction, and movement.
Mosquito:
- Mosquito is a multicellular organism belonging to the animal kingdom.
- It consists of various specialized cells that work together to perform life functions.
- The cells in a mosquito are divided into different tissues and organs, such as the nervous system, digestive system, respiratory system, etc.
Euglena:
- Euglena is a single-celled organism belonging to the group of protists.
- It can perform all life functions, including photosynthesis, movement, and reproduction.
Bacteria:
- Bacteria are single-celled organisms belonging to the group of prokaryotes.
- They can carry out all life functions necessary for their survival, such as metabolism, reproduction, and response to the environment.
Therefore, the correct answer is B: mosquito as it is a multicellular organism in which a single cell does not perform all life functions.

Tissue
- Cells with similar functions and structures come together to form tissues.
- Tissues are groups of cells that work together to perform a specific function.
- These specialized cells within the tissue can have similar shapes, sizes, and arrangements.
- There are four main types of tissues in the human body: epithelial, connective, muscle, and nervous.
- Each type of tissue has a specific function and is composed of cells that are specialized for that function.
- Examples of tissues include the epithelial tissue that lines the surfaces of organs and blood vessels, the connective tissue that supports and connects different body parts, the muscle tissue that allows movement, and the nervous tissue that transmits electrical signals.
- Tissues can form larger structures called organs when they work together with other tissues.
- Organs are composed of different types of tissues that collaborate to perform specific functions in the body.
- Therefore, the correct answer is C: tissue.

Which of these unicellular organisms has no definite shape?

The correct answer is amoeba.

Explanation:

• Amoeba: Amoeba is a type of unicellular organism that belongs to the group of protozoans. It has a flexible cell membrane, enabling it to change its shape constantly. As a result, amoeba does not have a definite shape.


• Euglena: Euglena is another unicellular organism that possesses a definite shape. It is a flagellate, characterized by a long whip-like tail called a flagellum, which helps in its movement.


• Bacteria: Bacteria are unicellular organisms that have a definite shape. They can be classified into different shapes such as spherical (cocci), rod-shaped (bacilli), or spiral (spirilla).


• Paramecium: Paramecium is a unicellular organism that belongs to the group of ciliates. It has a definite shape, usually described as an elongated slipper or cigar shape.

In conclusion, among the given options, amoeba is the unicellular organism that does not have a definite shape.

The cork-piece slide shows 1. dead cells.

Cork is composed of dead plant cells. When Robert Hooke first observed cork cells under a microscope, he saw only the cell walls because the cells were dead and the cytoplasm had disappeared.

The material between cell membrane and nucleus is called cytoplasm.
The cytoplasm is a jelly-like substance that fills the space between the cell membrane and the nucleus. It plays a crucial role in various cellular activities. Here are some key points about the cytoplasm:
1. Composition: The cytoplasm is composed of water, proteins, salts, and various organic molecules. It also contains organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, and ribosomes.
2. Functions: The cytoplasm performs several essential functions in the cell, including:
- Cellular metabolism: Many metabolic reactions occur in the cytoplasm, such as glycolysis, protein synthesis, and lipid metabolism.

- Transport: It serves as a medium for the transport of molecules and organelles within the cell. It also facilitates the movement of nutrients and waste products across the cell membrane.

- Support and shape: The cytoplasm provides structural support to the cell and helps maintain its shape.

- Storage: It acts as a storage site for various substances, including nutrients, ions, and waste products.

- Cellular communication: The cytoplasm is involved in intracellular signaling and communication processes, allowing cells to respond to external stimuli and coordinate their activities.

3. Organization: The cytoplasm is not a homogeneous mixture but is organized into different regions or compartments. These include the cytosol (the liquid portion), the cytoskeleton (protein fibers that provide structural support), and various organelles suspended within the cytosol.
In summary, the cytoplasm is the material between the cell membrane and the nucleus. It is a complex and dynamic environment that supports various cellular processes and is essential for the overall functioning of the cell.

Columnar epithelium cells
Columnar epithelium cells are a type of epithelial tissue that line the surfaces of organs and structures in the body. They are elongated and have a column-like shape.
Characteristics of columnar epithelium cells:
- Shape: Columnar epithelium cells are tall and cylindrical in shape.
- Nucleus: The nucleus of these cells is usually located towards the base of the cell, giving it an elongated appearance.
- Arrangement: These cells are often arranged in a single layer, forming a columnar shape.
- Functions: Columnar epithelium cells are involved in various functions such as absorption, secretion, and protection. They line the digestive tract, respiratory tract, and parts of the reproductive system.
- Modifications: Some columnar epithelium cells may have specialized modifications, such as microvilli or cilia, to aid in their specific functions.
Types of columnar epithelium:
- Simple columnar epithelium: Consists of a single layer of columnar cells and is found in areas where absorption and secretion take place, such as the lining of the stomach and intestines.
- Pseudostratified columnar epithelium: Appears stratified but is actually a single layer of columnar cells. It is found in the respiratory tract, where it helps to move mucus and trap particles.
- Transitional epithelium: Specialized columnar cells found in organs like the urinary bladder that can stretch and accommodate changes in volume.
In conclusion, columnar epithelium cells are elongated and column-like in shape. They play important roles in various functions within the body and can have different types and modifications depending on their location and function.

Align and branched animal cell is:
Answer: b. Reeve cell
Explanation:
To explain in detail, let's break down the information into bullet points:
- An animal cell refers to any of the cells that make up the tissues of animals. These cells are eukaryotic, meaning they have a nucleus and other membrane-bound organelles.
- An aligned and branched animal cell refers to a specific type of animal cell that has a distinctive alignment and branching pattern.
- The term "Reeve cell" is commonly used to describe this aligned and branched animal cell.
- Reeve cells are found in various tissues and organs of animals.
- These cells have a complex structure with multiple branches and extensions.
- The alignment and branching of these cells allow for efficient communication and coordination within the tissues.
- Reeve cells play important roles in functions such as cell signaling, nutrient transport, and tissue development.
- The specific functions of Reeve cells can vary depending on their location within the body and the type of tissue they are a part of.
In conclusion, an aligned and branched animal cell is commonly referred to as a Reeve cell. These cells have a complex structure with multiple branches and extensions, allowing for efficient communication and coordination within the tissues. Reeve cells play important roles in various functions within the body.

Longest Cell in Human Body
The longest cell in the human body is the nerve cell, also known as a neuron. Here is a detailed explanation of why the nerve cell is the longest:
1. Nerve Cell Structure:
- Neurons consist of a cell body, dendrites, and an axon.
- The cell body contains the nucleus and other organelles.
- Dendrites are branching structures that receive signals from other neurons.
- The axon is a long, slender projection that transmits signals to other cells.
2. Length of Nerve Cells:
- Nerve cells can vary in length, but some can be as long as several feet.
- For example, the sciatic nerve, which runs from the lower back to the foot, contains nerve cells that can extend up to 3 feet in length.
3. Function of Nerve Cells:
- Nerve cells are responsible for transmitting electrical signals throughout the body.
- They play a crucial role in the nervous system, enabling communication between different parts of the body.
4. Importance of Long Nerve Cells:
- The length of nerve cells allows for efficient transmission of signals over long distances.
- This enables coordination and communication between different parts of the body.
5. Other Cell Types:
- While other cells in the body, such as brain cells and skin cells, may have complex structures, they do not possess the same length as nerve cells.
Therefore, the nerve cell is the longest cell in the human body, allowing for the transmission of signals over long distances and enabling the functioning of the nervous system.

The largest cell in the world is an ostrich egg.
Explanation:
- An ostrich egg is considered the largest cell in the world.
- Ostrich eggs are about 6 inches in diameter and weigh around 1.4 kilograms (3 pounds).
- The size of an ostrich egg is significantly larger than the cells found in other organisms.
- Ostrich eggs are much larger than the cells found in turkeys, peafowls, and hens.
- While these animals may have large cells compared to other organisms, they are still much smaller than an ostrich egg.
- The size of an ostrich egg is necessary to support the development of a growing ostrich embryo.
- Ostriches are the largest birds in the world, and therefore, their eggs need to be large enough to accommodate the growth of the embryo.
- This large size allows for the storage of enough nutrients and resources to sustain the developing ostrich.
- It is important to note that while ostrich eggs are the largest cells, they are not considered individual organisms.
- Rather, they are part of a larger organism, the ostrich.
- Ostrich eggs are commonly used for various purposes, including cooking and crafting.

Glandular cells in epithelium have:
- Epithelial cells: Glandular cells are a type of epithelial cell, so they have epithelial cells.
- Goblet cells: Goblet cells are a type of glandular cell that produce and secrete mucus. Glandular cells in epithelium can include goblet cells.
- Turkey cells: There is no such term as "turkey cells" in relation to glandular cells in epithelium. This option is incorrect.
- Both (a) and (c): Since glandular cells are a type of epithelial cell and can include goblet cells, the correct answer is both (a) and (c).
To summarize, glandular cells in epithelium have epithelial cells and can include goblet cells.

Which unicellular organism has 2 nucleuses?
There is only one option that fits this description, which is:
Paramecium
Explanation:
- Paramecium is a unicellular organism that belongs to the group of ciliates.
- It is characterized by the presence of cilia, which are hair-like structures used for locomotion.
- Paramecium has two types of nuclei: a large macronucleus and one or more smaller micronuclei.
- The macronucleus controls everyday cellular functions, while the micronucleus is involved in sexual reproduction.
- The presence of two nuclei in Paramecium is an example of nuclear dimorphism.
In summary, among the given options, Paramecium is the only unicellular organism that has two nuclei.

Slides can be prepared and studied under a compound microscope.
Explanation:
Under a compound microscope, slides can be prepared and studied. This type of microscope uses multiple lenses to magnify the specimen and provide a detailed view of its structure. Slides are typically prepared by placing a thin slice of the specimen on a glass slide and covering it with a cover slip. The prepared slide is then placed on the stage of the compound microscope for observation.
Here are the reasons why slides can be prepared and studied under a compound microscope:
1. Magnification: Compound microscopes have a higher magnification power compared to dissecting microscopes. This allows for a more detailed examination of the specimen on the slide.
2. Resolution: Compound microscopes have better resolution, which means that they can distinguish between closely spaced structures on the slide. This is important for studying the fine details of the specimen.
3. Illumination: Compound microscopes are equipped with a built-in light source that provides uniform illumination of the specimen. This ensures that the entire slide is well-lit and visible under the microscope.
4. Objective lenses: Compound microscopes have a range of objective lenses with different magnification powers. This allows for the selection of the appropriate lens to study different aspects of the specimen on the slide.
In conclusion, compound microscopes are the ideal choice for preparing and studying slides due to their high magnification, resolution, illumination, and the availability of different objective lenses.

The correct answer is:

 Mycoplasma

Explanation:

• Mycoplasma is considered the smallest living cell, with a size ranging from 0.1 to 0.3 micrometers. It lacks a cell wall, which contributes to its small size and unique properties. Mycoplasma is a type of bacteria and is also the smallest self-replicating organism known to science.

• Red blood cells and yeast cells are much larger in comparison to Mycoplasma. Red blood cells typically have a diameter of about 6-8 micrometers, and yeast cells are usually around 3-4 micrometers in size.

So, Mycoplasma is the smallest cell in the living world.