Chapter-1 Nutrition In Plants Test-2 - Class 7 MCQ

Cells as Building Blocks

A cell is the smallest unit of a living thing. A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism. Thus, cells are the basic building blocks of all organisms.

When carbon dioxide, water, sunlight, and chlorophyll are present, photosynthesis occurs in plants. This process can be broken down into the following steps:
1. Absorption of Sunlight:
- Chlorophyll, a pigment found in the chloroplasts of plant cells, absorbs sunlight.
2. Splitting of Water:
- The absorbed sunlight energizes the electrons in chlorophyll, which leads to the splitting of water molecules (H2O).
3. Release of Oxygen:
- As water molecules split, oxygen (O2) is released as a byproduct.
4. Formation of Carbohydrates:
- The energized electrons from chlorophyll are used to convert carbon dioxide (CO2) into carbohydrates, such as glucose.
5. Utilization of Energy:
- The carbohydrates produced during photosynthesis can be used by the plant for energy, growth, and other metabolic processes.
Therefore, the correct answer is option C: Carbohydrate and oxygen are produced as a result of the photosynthesis process occurring in the presence of carbon dioxide, water, sunlight, and chlorophyll.

Stoma and its Surrounding Cells
The correct answer is B: Guard cells.
Explanation:
Stoma is a small opening found on the surface of plants, especially on the leaves and stems. It is responsible for gas exchange, allowing the entry of carbon dioxide for photosynthesis and the release of oxygen and water vapor.
The stoma is surrounded by a pair of specialized cells called guard cells. These cells play a crucial role in controlling the opening and closing of the stoma. Here's how they function:
1. Shape: The guard cells have a kidney or bean-shaped appearance. This shape allows them to create an opening or pore called the stomatal pore.
2. Cell Wall: The cell wall of the guard cells is unevenly thickened. The thickening is more pronounced on the inner side of the cell wall.
3. Cellular Arrangement: When the guard cells are flaccid or relaxed, the stomatal pore closes. When they are turgid or swollen, the stomatal pore opens.
4. Stomatal Opening: When the guard cells absorb water and become turgid, they expand and curve away from each other. This movement creates an opening in the center, forming the stomatal pore. This allows for gas exchange and facilitates the intake of carbon dioxide.
5. Stomatal Closure: When the guard cells lose water and become flaccid, they shrink and come closer together. This causes the stomatal pore to close, preventing excessive water loss through transpiration.
6. Regulation: The opening and closing of stomata are regulated by various environmental factors, including light intensity, temperature, humidity, and the plant's water status. These factors influence the movement of water into or out of the guard cells, thus controlling the turgidity and the opening or closing of the stomatal pore.
In conclusion, the pair of kidney-shaped cells surrounding a stoma are known as guard cells. They play a vital role in regulating the opening and closing of the stomatal pore, facilitating gas exchange and controlling water loss in plants.

Answer:
The water and minerals are absorbed by the roots of plants. Here is a detailed explanation:
Roots:
- The roots of a plant are responsible for absorbing water and minerals from the soil.
- They have tiny root hairs that increase the surface area for absorption.
- The root hairs are in close contact with the soil particles, allowing the plant to absorb water and dissolved minerals through osmosis and active transport.
Process of Absorption:
- The water enters the roots through the root hairs by the process of osmosis.
- The mineral ions dissolved in the soil water are actively transported into the root cells.
- The root cells then transfer the water and minerals to the xylem tissue, which acts as a transport system within the plant.
Role of Xylem:
- The xylem tissue is responsible for transporting water and minerals from the roots to the rest of the plant.
- It consists of specialized cells that form tubes, allowing for the movement of water and minerals through capillary action and transpiration pull.
Importance:
- Water and minerals absorbed by the roots are essential for various plant functions, such as photosynthesis, growth, and nutrient uptake.
- They provide the necessary hydration and nutrients for the plant's survival and overall health.
In summary, the roots of a plant are responsible for absorbing water and minerals from the soil, which are then transported to the rest of the plant through the xylem tissue.

Amoeba is an organism found in pond water.


Amoeba is a single-celled organism that belongs to the phylum Protozoa. It is commonly found in various aquatic environments, including pond water. Here is a detailed explanation of why amoeba is found in pond water:
1. Habitat:
- Amoeba thrives in freshwater habitats, such as ponds, lakes, and slow-moving streams.
- They can also be found in wet soil, marshes, and even in moist mosses.
- Pond water provides an ideal environment for amoeba due to its availability of nutrients and moisture.
2. Abundance:
- Ponds are often rich in organic matter, such as decaying plants, algae, and bacteria, which serve as a food source for amoeba.
- These organisms reproduce rapidly and can be found in large numbers in pond water.
3. Adaptability:
- Amoeba has the ability to adapt to different environmental conditions, including changes in temperature, pH levels, and nutrient availability.
- They can form cysts, a dormant stage that helps them survive unfavorable conditions, and then re-emerge when conditions become suitable.
4. Movement:
- Amoeba moves by extending finger-like projections called pseudopodia, allowing them to crawl and change their location within the water.
- This mobility enables them to locate food sources and avoid unfavorable conditions.
5. Interactions:
- In pond water, amoeba interacts with other microorganisms, such as bacteria and algae, forming a complex microbial ecosystem.
- They play a role in the decomposition of organic matter, recycling nutrients, and maintaining ecological balance in the pond.
In conclusion, amoeba is commonly found in pond water due to its adaptability, abundance of food sources, and favorable environmental conditions.

Mode of Nutrition: Saprotrophic Nutrition
Saprotrophic nutrition is the mode of nutrition in which organisms obtain nutrients from dead and decaying organic matter. This process involves the breakdown of complex organic compounds into simpler forms that can be absorbed and utilized by the organism. Fungi are the primary organisms that exhibit saprotrophic nutrition, although other organisms such as bacteria and some protists can also utilize this mode of nutrition.
Key Points about Saprotrophic Nutrition:
- Saprotrophs are also known as decomposers or detritivores, as they play a crucial role in the decomposition of organic matter in ecosystems.
- The dead and decaying matter, such as fallen leaves, wood, and animal carcasses, serve as the primary food source for saprotrophs.
- Saprotrophic organisms secrete enzymes that break down complex organic molecules, such as cellulose and lignin, into simpler molecules like sugars, amino acids, and fatty acids.
- These simpler molecules are then absorbed by the saprotrophs through their hyphae or other specialized structures.
- Saprotrophs help in the recycling of nutrients by decomposing organic matter and releasing the nutrients back into the environment, making them available for other organisms.
- This mode of nutrition is essential for the overall functioning and health of ecosystems.
Examples of Saprotrophs:
- Fungi: Mushrooms, molds, and yeasts are common examples of saprotrophic fungi.
- Bacteria: Certain bacteria, such as those belonging to the genus Bacillus and Clostridium, exhibit saprotrophic nutrition.
- Protists: Some protists, like slime molds and water molds, can also obtain nutrients through saprotrophic nutrition.
In conclusion, saprotrophic nutrition is the mode of nutrition in which organisms obtain nutrients from dead and decaying organic matter. Fungi are the primary organisms that exhibit this mode of nutrition, although bacteria and some protists can also utilize saprotrophic nutrition. This process plays a crucial role in the decomposition and recycling of organic matter in ecosystems.

Algae and fungus live together is called Lichens
Lichens are a unique type of organism that result from a symbiotic relationship between algae or cyanobacteria and fungi. Let's explore this in more detail:
1. Symbiotic Relationship:
- Lichens are formed when algae or cyanobacteria (which are photosynthetic) live together with fungi.
- The algae or cyanobacteria provide food through photosynthesis, while the fungi provide a protective environment and absorb minerals from their surroundings.
2. Structure of Lichens:
- Lichens can have various forms, including crusty, leafy, or shrubby appearances.
- The structure consists of an upper layer containing algae or cyanobacteria cells and a lower layer composed of fungal filaments.
3. Benefits of the Relationship:
- Algae or cyanobacteria produce food through photosynthesis and share it with the fungi.
- The fungi provide a protected environment and help in absorbing water and nutrients from the surroundings.
- Together, they can survive in extreme environments such as deserts, rocky surfaces, and polar regions.
4. Ecological Importance:
- Lichens are pioneers in colonizing barren surfaces, helping to initiate soil formation.
- They contribute to nitrogen fixation, making nutrients available for other organisms.
- Lichens are also indicators of air quality, as they are sensitive to pollution and can be used to monitor environmental changes.
5. Classification of Lichens:
- Lichens are classified based on their growth form, color, and reproductive structures.
- There are three main types: crustose (crusty), foliose (leafy), and fruticose (shrubby).
In conclusion, the symbiotic relationship between algae or cyanobacteria and fungi is called lichens. This unique partnership allows lichens to thrive in various environments and play important ecological roles.

State whether the following is true or false: product of photosynthesis is not a protein
Answer: True.
Photosynthesis is a process in which plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose (a sugar) and oxygen. The glucose produced during photosynthesis serves as the primary energy source for the plant, while oxygen is released as a byproduct.
Here is a detailed explanation of why the statement is true:
Photosynthesis and its products:
- Photosynthesis occurs in the chloroplasts of plant cells and involves several complex biochemical reactions.
- The primary product of photosynthesis is glucose, a simple sugar molecule.
- Glucose is an essential source of energy for the plant and is used in various metabolic processes.
- Additionally, glucose can be converted into other carbohydrates, such as starch, cellulose, and sucrose, for storage and transport within the plant.
Proteins and their synthesis:
- Proteins are macromolecules composed of amino acids and are involved in various cellular functions.
- Proteins are synthesized through a process called protein synthesis, which occurs in the ribosomes of the cell.
- Protein synthesis involves the transcription of DNA into messenger RNA (mRNA) and the translation of mRNA into a sequence of amino acids that form a protein.
- The amino acids required for protein synthesis are obtained from dietary sources or synthesized within the cell.
Difference between glucose (photosynthesis product) and proteins:
- Glucose is a simple sugar, while proteins are complex macromolecules composed of amino acids.
- Glucose is primarily involved in providing energy to the cell, while proteins have a wide range of functions, including structural support, enzymatic activity, and cell signaling.
- Glucose is directly produced during photosynthesis, while proteins are synthesized through a separate cellular process.
Therefore, we can conclude that the product of photosynthesis is not a protein.

The raw materials for photosynthesis include:
Light:
- Light energy is essential for the photosynthesis process to occur.
- It is captured by chlorophyll and other pigments in the chloroplasts of plant cells.
Organic Substances:
- Photosynthesis requires organic substances such as carbon dioxide and water.
- Carbon dioxide is obtained from the atmosphere through small openings called stomata on the surface of leaves.
- Water is absorbed by the roots of plants from the soil and transported to the leaves through specialized tissues.
Nutrients:
- In addition to carbon dioxide and water, plants also need various nutrients for photosynthesis.
- These include minerals such as nitrogen, phosphorus, and potassium, which are obtained from the soil.
- These nutrients are essential for the synthesis of organic molecules, such as proteins and nucleic acids, which are necessary for plant growth and development.
All of these:
- All of the above-mentioned raw materials are required for photosynthesis to occur.
- Light provides the energy needed for the process, while organic substances (carbon dioxide and water) and nutrients provide the building blocks for the synthesis of glucose and other organic molecules.
Overall, photosynthesis is a complex process that requires the presence of light, organic substances, and nutrients. These raw materials are essential for plants to produce glucose and oxygen, which are vital for their growth and survival.

Fungi is an example of Saprotrophs.
Saprotrophs are organisms that obtain their nutrients by decomposing dead organic matter. Fungi play a crucial role in the ecosystem as saprotrophs. Here's a detailed explanation:
What are Saprotrophs?
Saprotrophs are organisms that obtain their nutrition by breaking down dead organic matter. They secrete enzymes that break down complex organic compounds into simpler forms, which they can then absorb and utilize for their own growth and energy.
Why are Fungi considered Saprotrophs?
Fungi are heterotrophic organisms that obtain nutrients by external digestion. They secrete enzymes onto dead organic matter, such as dead plants, animals, and fecal matter, and break it down into simpler organic compounds. The fungi then absorb these compounds and utilize them for their growth and metabolism.
Characteristics of Saprotrophic Fungi:
- Fungi have hyphae, which are thread-like structures that allow them to penetrate and extract nutrients from their food source.
- They secrete enzymes, such as cellulases and proteases, which break down complex organic matter into simpler compounds.
- Fungi can thrive in diverse environments, including soil, decaying wood, and even inside other organisms.
Ecological Importance of Saprotrophic Fungi:
- Fungi play a vital role in nutrient cycling by decomposing dead organic matter and returning essential nutrients back to the ecosystem.
- They contribute to the decomposition of organic waste, aiding in waste management and recycling.
- Fungi are crucial for the breakdown of lignin, a complex organic compound found in plant cell walls, which facilitates the recycling of carbon in the environment.
In conclusion, fungi are a prime example of saprotrophs as they obtain their nutrients by decomposing dead organic matter. They have various adaptations and play a crucial role in nutrient cycling and ecosystem functioning.

The part of the plant that takes in carbon dioxide from the air for photosynthesis is the stomata.
Explanation:
The process of photosynthesis in plants requires carbon dioxide as one of the essential ingredients. The stomata, which are small openings found on the surface of leaves, play a crucial role in the exchange of gases between the plant and the environment. Here is a detailed explanation of how the stomata function in the uptake of carbon dioxide:
1. Structure of stomata:
- Stomata are surrounded by two specialized cells called guard cells.
- These guard cells can change shape to open or close the stomatal pore.
2. Opening and closing of stomata:
- The stomata open during the day and close during the night.
- They open in response to light, which triggers the guard cells to take up water and swell.
- When the guard cells swell, they create an opening for the exchange of gases.
3. Carbon dioxide uptake:
- When the stomata are open, carbon dioxide from the air enters the leaf through the stomatal pores.
- The concentration of carbon dioxide is usually higher in the external air compared to inside the leaf.
- This concentration gradient allows carbon dioxide to diffuse into the leaf through the stomata.
4. Inside the leaf:
- Once inside the leaf, carbon dioxide is used during the process of photosynthesis.
- It enters the chloroplasts, where it combines with water and sunlight to produce glucose and oxygen.
In conclusion, the stomata are responsible for the uptake of carbon dioxide from the air, allowing plants to perform photosynthesis and produce energy-rich carbohydrates.

Plants take carbon dioxide from the atmosphere mainly through their leaves.



Plants use a process called photosynthesis to convert carbon dioxide from the atmosphere into carbohydrates, which they use as energy for growth and development. The leaves of plants play a crucial role in this process.



Here's a detailed explanation of how plants take carbon dioxide through their leaves:



1. Leaf Structure:

- Leaves are the primary site of photosynthesis in plants.

- They have a large surface area and are usually broad and flat, which allows for maximum exposure to sunlight.

- The outer layer of the leaf is covered by a waxy cuticle, which helps reduce water loss.



2. Stomata:

- Tiny pores called stomata are present on the surface of leaves.

- Stomata allow gases, including carbon dioxide, to enter and exit the leaf.

- They are surrounded by two specialized cells called guard cells, which control the opening and closing of the stomata.



3. Gas Exchange:

- When the stomata are open, carbon dioxide from the atmosphere diffuses into the leaf.

- The concentration of carbon dioxide is higher in the atmosphere than inside the leaf, so it moves from an area of high concentration to an area of low concentration.

- The presence of chlorophyll in the chloroplasts within the leaf cells helps capture the energy from sunlight to power the photosynthesis process.



4. Photosynthesis:

- Inside the leaf, carbon dioxide combines with water in the presence of sunlight and chlorophyll to undergo photosynthesis.

- During this process, carbon dioxide is converted into glucose (a type of carbohydrate) and oxygen is released as a byproduct.

- The glucose produced is then used by the plant for energy and growth.



5. Transpiration:

- Along with carbon dioxide uptake, the process of transpiration also takes place through the leaves.

- Transpiration is the loss of water vapor from the plant through the stomata.

- As water evaporates from the leaf surface, it creates a pulling force that helps transport water and nutrients from the roots to the leaves.



In conclusion, plants primarily take in carbon dioxide from the atmosphere through their leaves. The leaves have specialized structures like stomata and chloroplasts that facilitate gas exchange and photosynthesis, allowing the plants to convert carbon dioxide into energy-rich carbohydrates.

Organisms and Energy Utilization
Organisms require energy for their growth and maintenance. This energy is obtained from various sources, and one of the primary sources is food. Here is a detailed explanation of why organisms need food and how they utilize it for energy:
1. Importance of Food:
- Food provides essential nutrients, such as carbohydrates, proteins, and fats, which are necessary for the proper functioning of cells and tissues.
- It supplies energy in the form of calories that are used for various biological processes.
- Food contains vitamins and minerals that are required for maintaining good health and preventing deficiencies.
2. Energy Acquisition:
- Organisms obtain food through different methods depending on their nutritional requirements. For example:
- Autotrophs (plants, algae) produce their food through photosynthesis by utilizing sunlight, water, and carbon dioxide.
- Heterotrophs (animals, fungi) consume other organisms or their byproducts to obtain energy.
3. Energy Conversion:
- Once food is consumed, it undergoes various processes to release energy. These processes include digestion, absorption, and cellular respiration.
- Digestion breaks down complex molecules into simpler forms that can be absorbed by the body.
- Absorption allows the nutrients to enter the bloodstream and reach the cells.
- Cellular respiration occurs in the mitochondria of cells, where nutrients are further broken down to produce adenosine triphosphate (ATP), the energy currency of cells.
4. Energy Utilization:
- ATP generated from the breakdown of nutrients is utilized by cells for various purposes:
- Growth and development: Energy is required for the synthesis of new molecules, cell division, and tissue repair.
- Maintenance: Energy is used to maintain body temperature, perform daily activities, and support metabolic processes.
- Muscle contraction: Energy is utilized for muscle movement and physical activities.
- Nerve transmission: Energy is needed for transmitting signals within the nervous system.
In conclusion, all organisms require food as a source of energy for their growth and maintenance. Food provides the necessary nutrients and calories that are converted into ATP through digestion, absorption, and cellular respiration. This ATP is then utilized by cells for various biological processes, ensuring the proper functioning of the organism.

The process by which green plants synthesize food for themselves is called photosynthesis. Photosynthesis is a complex biochemical process that occurs in the chloroplasts of plant cells. Here is a detailed explanation of photosynthesis:
1. Definition:
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose.
2. Chloroplasts:
Photosynthesis takes place in specialized organelles within plant cells called chloroplasts. Chloroplasts contain a green pigment called chlorophyll, which is responsible for capturing light energy.
3. Light-dependent reactions:
The first stage of photosynthesis is the light-dependent reactions. During this stage, light energy is absorbed by chlorophyll and used to split water molecules into oxygen and hydrogen ions. This process generates ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy-rich molecules.
4. Calvin cycle:
The second stage of photosynthesis is the Calvin cycle, also known as the light-independent reactions or dark reactions. In this stage, carbon dioxide from the atmosphere is combined with the hydrogen ions and energy from the light-dependent reactions to produce glucose, which is the primary source of energy for the plant.
5. Oxygen production:
One of the byproducts of photosynthesis is oxygen. The oxygen is released into the atmosphere as a waste product, which is essential for the survival of other organisms.
6. Factors affecting photosynthesis:
Several factors can affect the rate of photosynthesis, including light intensity, carbon dioxide concentration, temperature, and the availability of water and nutrients.
In conclusion, photosynthesis is the process by which green plants synthesize food for themselves. It involves the conversion of light energy into chemical energy, resulting in the production of glucose and oxygen.

Plants like cuscuta are parasites. They take food from the host plant.
Explanation:
Parasitic plants, such as cuscuta, obtain their nutrients and energy by attaching themselves to a host plant and extracting resources from it. In this case, cuscuta takes food from the host plant.
Here is a detailed explanation:
What are parasites?
- Parasites are organisms that live in or on another organism (host) and obtain nutrients from it.
- They rely on the host for their survival and reproduction.
Characteristics of cuscuta:
- Cuscuta, commonly known as dodder, is a genus of parasitic plants.
- It does not have chlorophyll and cannot produce its own food through photosynthesis.
- Instead, it relies on other plants for its nutrition.
How cuscuta obtains food from the host plant:
- Cuscuta attaches itself to the host plant using specialized structures called haustoria.
- Haustoria penetrate the host plant's tissues and establish a connection between cuscuta and the host.
- Through this connection, cuscuta extracts water, nutrients, and carbohydrates from the host plant.
- It essentially leeches off the host plant's resources to sustain its growth and reproduction.
Impact on the host plant:
- The presence of cuscuta can have negative effects on the host plant.
- It competes with the host plant for resources, leading to stunted growth or even death of the host in severe cases.
- Cuscuta can also transmit diseases between plants, further harming the host plant.
In conclusion, cuscuta is a parasitic plant that depends on a host plant for its nutrition. It attaches itself to the host and extracts water, nutrients, and carbohydrates from it, which can have detrimental effects on the host plant.

Plants use simple chemical substances like carbon dioxide, water, and minerals for the synthesis of food through the process of photosynthesis.
Explanation:
- Plants require several essential elements to carry out the process of photosynthesis, which enables them to produce food for their growth and survival.
- Carbon dioxide (CO2) is obtained from the atmosphere through small openings called stomata in the leaves. It is one of the primary raw materials used by plants during photosynthesis.
- Water (H2O) is absorbed by the plant's roots from the soil. It is transported through the stems to the leaves, where it is used in the photosynthetic process.
- Minerals, such as nitrogen, phosphorus, and potassium, are essential nutrients that plants obtain from the soil. These minerals are involved in various metabolic processes and are crucial for plant growth and development.
- During photosynthesis, plants convert carbon dioxide and water into glucose, a simple sugar, which serves as the primary source of energy for the plant. This glucose is used to synthesize other complex carbohydrates, proteins, and lipids.
- The process of photosynthesis occurs in specialized structures called chloroplasts, which contain a pigment called chlorophyll that captures sunlight energy necessary for the synthesis of food.
- Overall, plants utilize the simple chemical substances of carbon dioxide, water, and minerals to carry out photosynthesis and synthesize food, enabling their growth and survival.

Photosynthesis: The Essential Requirements
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. The essential requirements for photosynthesis are:
1. Chlorophyll: Chlorophyll is a green pigment found in the chloroplasts of plant cells. It absorbs light energy from the sun, which is essential for the photosynthetic process.
2. Water: Water is a crucial component of photosynthesis. It is absorbed by the roots of plants and transported to the leaves where it is used in the light-dependent reactions of photosynthesis.
3. Carbon Dioxide: Carbon dioxide is a gas that is taken in by plants from the atmosphere. It enters the leaves through tiny openings called stomata and is used in the process of photosynthesis to produce glucose.
4. Sunlight: Sunlight is the source of energy for photosynthesis. It provides the necessary light energy that is absorbed by chlorophyll to convert carbon dioxide and water into glucose.
In summary, chlorophyll, water, carbon dioxide, and sunlight are the essential requirements for photosynthesis. Without any of these components, the process of photosynthesis cannot occur efficiently.

Answer:
The complex chemical substances that are products of photosynthesis include carbohydrates. Here is a detailed explanation:
Photosynthesis:
- Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy.
- It occurs in the chloroplasts of plant cells, specifically in the chlorophyll pigment.
Products of Photosynthesis:
- The main products of photosynthesis are glucose (a simple sugar) and oxygen.
- Glucose is a carbohydrate and serves as the primary source of energy for plants.
- Oxygen is released into the atmosphere as a byproduct of photosynthesis.
Complex Chemical Substances:
- Carbohydrates are complex chemical substances that consist of carbon, hydrogen, and oxygen atoms.
- They are formed during photosynthesis through the combination of carbon dioxide and water in the presence of sunlight.
- Examples of carbohydrates produced through photosynthesis include glucose, sucrose, cellulose, and starch.
Other Options:
- Cellulose is a type of carbohydrate that provides structural support in plant cell walls.
- Vitamins are organic compounds that are necessary in small amounts for proper functioning of the body, but they are not directly produced through photosynthesis.
- Proteins are macromolecules composed of amino acids and are not directly produced through photosynthesis.
Therefore, the correct answer is Carbohydrate (Option B) as the complex chemical substances produced through photosynthesis.

Answer:
Oxygen is produced during photosynthesis.

Explanation:
During photosynthesis, plants use sunlight, water, and carbon dioxide to convert them into glucose (a type of sugar) and oxygen. This process takes place in the chloroplasts of plant cells, specifically in the green pigment called chlorophyll. The oxygen produced during photosynthesis is released into the atmosphere as a byproduct.
Here is a detailed explanation of each option:
A. Photosynthesis:
- Plants, algae, and some bacteria perform photosynthesis.
- During photosynthesis, plants convert sunlight, water, and carbon dioxide into glucose and oxygen.
- Oxygen is released as a byproduct of this process.
B. Respiration:
- Respiration is the process by which living organisms convert glucose and oxygen into energy, carbon dioxide, and water.
- In respiration, oxygen is consumed rather than produced.
- It is the opposite process of photosynthesis.
C. Transpiration:
- Transpiration is the process by which plants lose water through their leaves.
- It does not directly involve the production of oxygen.
D. Breathing:
- Breathing is the process by which organisms take in oxygen and release carbon dioxide.
- Oxygen is consumed during breathing, not produced.
In conclusion, oxygen is produced during photosynthesis (option A).

Heterotrophs
- Heterotrophs are organisms that cannot produce their own food and rely on other organisms for nutrition.
- They obtain their energy and nutrients by consuming organic material from other organisms.
- Heterotrophs can be further classified into different types based on their feeding strategies.
- Herbivores are heterotrophs that primarily feed on plants.
- Carnivores are heterotrophs that primarily feed on other animals.
- Omnivores are heterotrophs that consume both plant and animal matter.
- Decomposers are heterotrophs that obtain nutrients by breaking down dead organic material.
- Parasites are heterotrophs that live in or on other organisms and obtain nutrients from them.
- Heterotrophs are an essential part of the food chain, as they help to transfer energy and nutrients from one organism to another.
- Without heterotrophs, the energy flow and nutrient cycling in ecosystems would be disrupted.
Examples of Heterotrophs:
- Humans
- Dogs
- Cats
- Lions
- Cows
- Birds
- Insects
- Fungi (such as mushrooms)
- Bacteria (such as those involved in decomposition)