SA I - Full Biology Test - Class 9 MCQ

Explanation:
The correct answer is C. Bordeaux mixture.
Fungicides:
- Fungicides are chemicals that are used to control or kill fungi that cause diseases in plants.
- They are applied to plants to protect them from fungal infections and to prevent the spread of diseases.
Options:
A: 2-4
- 2-4 is not a fungicide. It is a common name for a herbicide known as 2,4-Dichlorophenoxyacetic acid.
B: DDT
- DDT is not a fungicide. It is a pesticide that was widely used in the past but is now banned in many countries due to its harmful effects on the environment and human health.
C: Bordeaux mixture
- Bordeaux mixture is a fungicide and bactericide that is widely used in agriculture to control fungal and bacterial diseases in plants.
- It is a mixture of copper sulfate and hydrated lime and is effective against a wide range of plant pathogens.
D: BHC
- BHC (Benzene hexachloride) is not a fungicide. It is an insecticide that was commonly used in the past but is now banned in many countries due to its persistence in the environment and its harmful effects on human health.
In conclusion, the correct answer is C. Bordeaux mixture, which is a fungicide used to control fungal and bacterial diseases in plants.

The radiant energy of sunlight is converted to chemical energy and stored as ATP. Here is a detailed explanation:
1. Sunlight as a source of energy:
- Sunlight is a form of electromagnetic radiation that contains energy.
- Plants and some microorganisms have the ability to capture this energy and convert it into a usable form.
2. Photosynthesis:
- The process by which plants convert sunlight into chemical energy is called photosynthesis.
- During photosynthesis, plants use pigments such as chlorophyll to capture sunlight in their leaves.
3. Formation of ATP:
- The captured sunlight energy is used to convert ADP (adenosine diphosphate) into ATP (adenosine triphosphate).
- ATP is a high-energy molecule that can be used by cells as a source of energy for various metabolic processes.
4. Storage of ATP:
- ATP is not stored in large quantities within cells because it is a highly reactive molecule.
- Instead, cells store ATP in small amounts and constantly regenerate it as needed.
5. ATP as an energy currency:
- ATP is considered the "energy currency" of the cell because it can be easily hydrolyzed to release energy.
- When ATP is hydrolyzed, it forms ADP and inorganic phosphate (Pi), releasing energy that can be used by the cell.
In conclusion, the radiant energy of sunlight is converted to chemical energy and stored as ATP through the process of photosynthesis. ATP serves as an immediate source of energy for cellular processes.

The Longest Cell in the Human Body
The longest cell in the human body is the neuron. Neurons are specialized cells that transmit electrical and chemical signals throughout the body. They form the basic building blocks of the nervous system and play a crucial role in communication between different parts of the body.
Why is the Neuron the Longest Cell?
The length of a neuron can vary depending on its location and function. However, some neurons can be incredibly long, spanning from the spinal cord to the tips of the toes or from the spinal cord to the fingertips. These long neurons are called projection neurons or efferent neurons.
Key Points:
- Neurons are the longest cells in the human body.
- They transmit electrical and chemical signals.
- Some neurons can span from the spinal cord to the tips of the toes or fingertips.
- These long neurons are called projection neurons or efferent neurons.
- Neurons play a crucial role in communication within the body.
- Their length allows for long-distance signaling and coordination.

Explanation:
The term "protoplasm" refers to the living substance present inside the cell. It was given by J.E. Purkinje.
Robert Hooke:
- Robert Hooke was an English scientist who coined the term "cell" to describe the basic building blocks of life.
- He also made significant contributions to the field of microscopy.
Robert Brown:
- Robert Brown was a Scottish botanist who discovered and described the nucleus of the cell.
- However, he did not give the term "protoplasm" to the living substance inside the cell.
J.E. Purkinje:
- J.E. Purkinje was a Czech anatomist and physiologist.
- He is credited with coining the term "protoplasm" in 1839 to describe the living substance found inside the cell.
W. Flemming:
- W. Flemming, also known as Walther Flemming, was a German biologist.
- He is best known for his work on cell division and the discovery of chromatin.
- However, he did not give the term "protoplasm" to the living substance inside the cell.
Therefore, the correct answer is C: J.E. Purkinje.

Introduction:
In this question, we are asked to identify which of the given options are made of dead cells. Let's analyze each option and determine the correct answer.
Analysis:
The given options are:
A. Sclerenchyma
B. Tracheids
C. Vessels
D. All the above
Let's discuss each option in detail:
1. Sclerenchyma:
- Sclerenchyma is a type of plant tissue.
- It provides support and mechanical strength to the plant.
- Sclerenchyma cells are dead at maturity.
- Therefore, option A is made of dead cells.
2. Tracheids:
- Tracheids are long, narrow cells found in xylem tissue of plants.
- They transport water and minerals throughout the plant.
- Tracheids are dead cells at maturity.
- Therefore, option B is made of dead cells.
3. Vessels:
- Vessels are also part of the xylem tissue in plants.
- They are tube-like structures formed by the arrangement of vessel elements.
- Vessels transport water and dissolved substances.
- Vessels are dead cells at maturity.
- Therefore, option C is made of dead cells.
Conclusion:
From the analysis above, we can conclude that all the given options (A, B, and C) are made of dead cells. Therefore, the correct answer is option D.

Answer:
The pair of kidney-shaped cells present around stomata are called guard cells. Here is a detailed explanation of the answer:
1. What are stomata?
- Stomata are tiny openings or pores present on the surface of leaves, stems, and other plant organs.
- They are surrounded by specialized cells called guard cells.
2. What are guard cells?
- Guard cells are two bean-shaped or kidney-shaped cells that surround and control the opening and closing of stomata.
- They are usually found in pairs, with a gap between them called the stomatal pore.
3. Function of guard cells:
- The main function of guard cells is to regulate the exchange of gases, such as carbon dioxide and oxygen, between the plant and its environment.
- They control the opening and closing of stomata to facilitate the exchange of gases and prevent excessive water loss through transpiration.
4. Structure of guard cells:
- Guard cells have a thickened inner wall and a thinner outer wall, which allows them to change shape.
- When the guard cells are turgid (swollen with water), they curve and create an opening, allowing gas exchange.
- When the guard cells lose water and become flaccid, they shrink, closing the stomatal pore and preventing water loss.
5. Other options:
- Subsidiary cells: These are specialized cells surrounding the guard cells but do not have a kidney shape like guard cells.
- Epidermal cells: These are the outermost layer of cells in the plant epidermis and do not specifically surround stomata.
- Trichomes: These are hair-like outgrowths on the surface of plants and are not directly associated with stomata.
Therefore, the correct answer is option A: Guard cells.

Tendon connects a:
A: Ligament with muscle
- A ligament connects bone to bone, not muscle.
B: Bone with muscle
- Tendons are tough fibrous connective tissues that connect muscle to bone. They transmit the force generated by the muscle to the bone, allowing movement and providing stability.
C: Cartilage with muscle
- Cartilage is a type of connective tissue that provides cushioning and support between bones. It does not directly connect with muscles.
D: Bone with bone
- Ligaments are the connective tissues that connect bone to bone, not tendons.
Therefore, the correct answer is B: Tendon connects bone with muscle. Tendons play a crucial role in enabling movement and providing stability by transmitting the force generated by the muscle to the bone.

Longitudinal Canals of the Bone
The longitudinal canals of the bone are called Haversian canals. Here is a detailed explanation:
1. Haversian Canals:
- The Haversian canals, also known as osteons, are microscopic canals found in compact bone.
- They run parallel to the long axis of the bone and contain blood vessels, nerves, and connective tissue.
- These canals play a crucial role in the transport of nutrients, oxygen, and waste products to and from the bone cells.
2. Structure:
- Each Haversian canal is surrounded by concentric layers of bone tissue called lamellae.
- The lamellae are arranged in a circular fashion around the canal, forming a structural unit known as an osteon.
- Osteocytes, which are bone cells, are found within the spaces between the lamellae and are connected to each other via tiny channels called canaliculi.
3. Function:
- Haversian canals help in the maintenance and repair of bone tissue.
- They provide a network for the exchange of nutrients and waste products between the bone cells and the blood supply.
- The canaliculi allow for communication and transport of substances between osteocytes, ensuring their survival and proper functioning.
In conclusion, the longitudinal canals of the bone are called Haversian canals. They are essential for the overall health and functioning of bone tissue by facilitating the transport of nutrients and waste products.

The bone marrow is composed of:

A: Muscle fibres and adipose tissue

B: Areolar tissue and adipose tissue

C: Adipose tissue and calcified cartilage

D: Adipose tissue, areolar tissue, and blood vessels

Answer: D

Detailed

The bone marrow is a soft, gelatinous tissue found inside the hollow spaces of bones. It is responsible for the production of blood cells and is composed of various components. Here is a detailed explanation of the composition of bone marrow:

1. Adipose Tissue: Adipose tissue, also known as fat tissue, is a major component of bone marrow. It serves as a storage site for fat cells and provides insulation and cushioning.

2. Areolar Tissue: Areolar tissue, also called loose connective tissue, is another component of bone marrow. It is a flexible and fibrous tissue that provides support and elasticity to the bone marrow.

3. Blood Vessels: Bone marrow is highly vascularized, meaning it contains a network of blood vessels. These blood vessels supply oxygen, nutrients, and hormones to the bone marrow and carry away waste products.

Overall, the bone marrow is composed of adipose tissue, areolar tissue, and blood vessels. These components work together to support the production and maturation of blood cells within the bone marrow.

Blood plasma is slightly alkaline.
Blood plasma is the liquid component of blood that makes up about 55% of the total blood volume. It is composed of water, electrolytes, proteins, hormones, and waste products. The pH of blood plasma refers to its level of acidity or alkalinity, and it is measured on a scale of 0 to 14.
Explanation:
The pH scale ranges from 0 to 14, with 7 being neutral. A pH below 7 is considered acidic, while a pH above 7 is alkaline. Blood plasma has a slightly alkaline pH, typically ranging from 7.35 to 7.45.
Reasoning:
- Blood plasma contains various electrolytes, including bicarbonate ions, which help maintain the pH balance in the body.
- The body's normal pH range is tightly regulated to ensure optimal functioning of enzymes and other biochemical processes.
- When the pH of blood plasma deviates from the normal range, it can lead to health issues such as acidosis (lower pH) or alkalosis (higher pH).
- The slightly alkaline nature of blood plasma is essential for maintaining the acid-base balance in the body and supporting various physiological processes.
Therefore, the correct answer is C:

Slightly alkaline

.

Organelles lacking membranes:
- Ribosome
Organelles with membranes:
- Mitochondria
- Golgi complex
- Nucleus
Explanation:
Organelles are specialized structures found within cells that perform specific functions. Some organelles are surrounded by a membrane, while others lack a membrane. In this case, we are asked to identify the organelles that lack membranes.
1. Ribosome:
- Ribosomes are small, spherical structures involved in protein synthesis.
- They can be found either freely floating in the cytoplasm or attached to the endoplasmic reticulum.
- Ribosomes lack a membrane and are composed of ribosomal RNA (rRNA) and proteins.
2. Mitochondria:
- Mitochondria are double-membrane organelles responsible for generating energy in the form of ATP through cellular respiration.
- They have an outer membrane and an inner membrane with folds called cristae.
- Mitochondria are not included in the organelles lacking membranes.
3. Golgi complex:
- The Golgi complex, also known as the Golgi apparatus, is involved in modifying, sorting, and packaging proteins and lipids for transport to their final destinations.
- It consists of a series of flattened membrane-bound sacs called cisternae.
- The Golgi complex is not included in the organelles lacking membranes.
4. Nucleus:
- The nucleus is the control center of the cell and contains the genetic material in the form of DNA.
- It is surrounded by a double membrane called the nuclear envelope, which has nuclear pores for communication with the cytoplasm.
- The nucleus is not included in the organelles lacking membranes.
Therefore, the correct answer is A: Ribosome, as it is the only organelle mentioned that lacks a membrane.

Cell vacuole contains:
- Water: The cell vacuole contains a large amount of water, which helps maintain the turgidity and shape of the cell.
- Dissolved substances: Various dissolved substances such as sugars, salts, amino acids, and minerals are present in the vacuole. These substances are important for cellular processes and storage.
- Ions: The vacuole also contains ions like potassium, calcium, and chloride, which are essential for maintaining the cell's osmotic balance and regulating various cellular functions.
- Pigments: Some vacuoles contain pigments that give color to certain plant parts, such as flower petals or fruits.
- Waste products: The vacuole also serves as a storage site for waste products, including toxins and metabolic by-products. This prevents these substances from harming other cellular components.
- Secondary metabolites: Some vacuoles store secondary metabolites, which are compounds produced by the cell that are not directly involved in growth or survival but have functions such as defense against pathogens or attracting pollinators.
Overall, the cell vacuole plays a crucial role in maintaining cellular homeostasis, storing essential substances, and regulating various cellular processes.

Autotrophs are organisms which:
Autotrophs are organisms that are capable of producing their own food through the process of photosynthesis or chemosynthesis. They are self-sustaining and do not rely on other organisms for their nutrition. Autotrophs play a vital role in the food chain as they are the primary producers of organic compounds.
Autotrophs make their own food through:
- Photosynthesis: Most autotrophs, including plants, algae, and some bacteria, use photosynthesis to convert sunlight, water, and carbon dioxide into glucose and oxygen. This process takes place in specialized organelles called chloroplasts.
- Chemosynthesis: Some autotrophic bacteria and archaea use chemosynthesis to produce food. They derive energy from inorganic compounds such as hydrogen sulfide or methane, instead of sunlight, to synthesize organic molecules.
Key points:
- Autotrophs are self-sustaining organisms that produce their own food.
- They are the primary producers in the food chain.
- Autotrophs use photosynthesis or chemosynthesis to make their own food.
- Photosynthetic autotrophs convert sunlight, water, and carbon dioxide into glucose and oxygen.
- Chemosynthetic autotrophs derive energy from inorganic compounds to synthesize organic molecules.

Characteristics of Angiosperms:
- Angiosperms are flowering plants that produce seeds enclosed within a fruit.
- They are the most diverse group of plants, with over 300,000 known species.
- Angiosperms have several unique characteristics that distinguish them from other plant groups.
Characteristics of Angiosperms include:
1. Vessels: Angiosperms have specialized conducting cells called vessels in their xylem, which aid in the efficient transport of water and minerals throughout the plant.
2. Sieve Tubes: Angiosperms have sieve tubes, which are specialized cells responsible for the transport of sugars and organic nutrients within the plant. These sieve tubes are part of the phloem tissue.
3. Cambium: Angiosperms possess a cambium layer, which is a meristematic tissue that allows for secondary growth. The cambium is responsible for the production of new xylem and phloem cells, contributing to the increase in girth of the plant.
4. Flowers: Angiosperms produce flowers, which are reproductive structures involved in the production of seeds. Flowers are typically composed of petals, sepals, stamens (male reproductive organs), and pistils (female reproductive organs).
5. Fruits: Angiosperms produce fruits, which are mature ovaries containing seeds. Fruits aid in seed dispersal and protect the developing seeds.
6. Double Fertilization: Angiosperms undergo a unique process called double fertilization, where one sperm fertilizes the egg to form the embryo, and another sperm fuses with the polar nuclei to form the endosperm, a nutritive tissue for the developing embryo.
7. Reduced Gametophytes: Angiosperms have reduced gametophytes, with the male gametophyte (pollen grain) and female gametophyte (embryo sac) being small and dependent on the sporophyte plant.
Overall, angiosperms exhibit a range of characteristics that have contributed to their evolutionary success and dominance in the plant kingdom.