Extra Questions for Chapter 10 Life Processes in Plants Class 7 Science Curiosity
Class 10 Life Processes in Plants Extra Questions
Very Short Answer Questions
Question 1. What do you mean by nutrition?
Answer
Nutrition is the mode of taking food by an organism and its utilization by the body.
Question 2.Why are algae present in stagnant water bodies green in colour?
Answer
Because they contain the green pigment chlorophyll.
Question 3. Name some components of food.
Answer
Carbohydrates, proteins, fats, vitamins, and minerals.
Question 4. Why is photosynthesis named so?
Answer
Photosynthesis named so the because synthesis of food occurs in the presence of sunlight.
Question 5. Name a plant that has both autotrophic and heterotrophic modes of nutrition.
Answer
Insectivorous plants.
Question 6. What do plants need to grow?
Answer
Plants need sunlight, water, air, and nutrients to grow.
Question 7. How do plants make their own food?
Answer
Plants make food through photosynthesis.
Question 8. Where does photosynthesis mainly take place?
Answer
Photosynthesis mainly takes place in leaves.
Question 9. What do roots absorb from the soil?
Answer
Roots absorb water and minerals.
Question 10. What does the phloem do in plants?
Answer
Phloem is a tissue that carries food (glucose or starch) made in the leaves to non-green parts like roots, stems, and fruits for growth and storage.
Question 11. What is photosynthesis?
Answer
Photosynthesis is the process by which plants use sunlight, chlorophyll, carbon dioxide, and water to produce glucose and oxygen. It mainly occurs in the leaves.
Question 12. Why are leaves called the "food factories" of plants?
Answer
Leaves are called the "food factories" because they perform photosynthesis, producing food (glucose) for the plant using sunlight, water, and carbon dioxide.
Question 13. What is the role of chlorophyll in plants?
Answer
Chlorophyll is a green pigment in leaves that captures sunlight, which is necessary for photosynthesis. It helps convert light energy into chemical energy to produce food.
Question 14. What happens to the starch produced by plants during photosynthesis?
Answer
The starch produced in plants is stored for later use. It serves as a carbohydrate reserve that can be converted into glucose when needed for energy.
Short Answer Questions
Question 1. What is Symbiosis? What is a symbiotic relationship?
Answer
Symbiosis is a close, long-term relationship between two different organisms where both benefit, often involving sharing of nutrients, shelter, or other resources.- Example: In lichens, algae provide nutrients via photosynthesis, and fungi provide shelter and water.
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| Symbiotic Relationship |
Question 2. What happens during plant respiration?
Answer
During respiration, plants break down glucose using oxygen to release energy, carbon dioxide, and water. This energy helps plants grow and do other functions.
Question 3. Why do leaves need chlorophyll for photosynthesis?
Answer
Chlorophyll is a green pigment in leaves that captures sunlight. It uses this sunlight energy to combine carbon dioxide and water to make food (glucose), which is why it’s essential for photosynthesis.
Question 4. What is plant respiration and how is it different from photosynthesis?
Answer
Respiration is the process where plants break down glucose using oxygen to release energy. It happens in all parts of the plant.
The word equation is:
Glucose + Oxygen → Carbon dioxide + Water + Energy.
Unlike photosynthesis, which occurs only in green parts and in light, respiration happens all the time and in all parts of the plant.
Question 5. What is the ultimate source of energy for all living organisms?
Answer
Sun is the ultimate source of energy for all living organisms.
- It provides the necessary light energy that plants use to perform photosynthesis, which is the foundation of most food chains.
- Plants convert this solar energy into chemical energy in the form of glucose, which is then consumed by herbivores and further by carnivores, making the sun essential for life on Earth.
Question 6. What is the role of leaves in food preparation? How is starch tested in a leaf?
Answer
Leaves act as the food factories of plants because they contain chlorophyll and capture sunlight. They use sunlight, water, and carbon dioxide to make food. The food is stored as starch. To test for starch, the leaf is boiled and treated with iodine solution. If starch is present, it turns blue-black in colour.
Question 7. Describe how water and minerals are transported in plants.
Answer
Water and minerals are absorbed by the roots from the soil. These are transported upward to the stems, leaves, and flowers through xylem tissue. The xylem acts like a pipeline. This supply is necessary for photosynthesis and plant growth. Without water, plants can wilt or die.
Question 8. How do plants transport food to different parts of the body?
Answer
Food made in the leaves through photosynthesis is sent to all parts of the plant. The phloem tissue carries glucose and starch from the leaves to roots, stems, and fruits. This ensures that even non-green parts of the plant get the energy they need to grow and store food.
Question 9. What are stomata? Explain their function.
Answer
Stomata are tiny pores on the underside of the leaf surface that are surrounded by guard cells.
Functions:
To exchange gases by diffusion for photosynthesis and respiration and to cause transpiration by evaporation of water from the leaf surface.
- Gas Exchange: Allowing carbon dioxide to enter the leaf for photosynthesis and oxygen to exit as a by-product.
- Transpiration: Enabling water vapour to leave the plant, helping to regulate temperature and maintain nutrient flow.
Question 10. From where do plants get raw materials to prepare their food?
Answer
Plants get raw materials to prepare their food from their surroundings.
- Carbon Dioxide: Absorbed from the air through stomata in the leaves.
- Water: Taken up from the soil through the roots.
- Sunlight: Captured by chlorophyll in the leaves. The energy from sunlight is crucial for converting carbon dioxide and water into glucose.
Question 11. How does the iodine test show that leaves produce starch during photosynthesis?
Answer
- The iodine test shows starch in leaves by turning them blue-black.
- You take a leaf exposed to sunlight, decolourise it to remove green colour, and add iodine solution.
If the leaf turns blue-black, it means starch (made during photosynthesis) is present.
A leaf kept in darkness won’t turn blue-black because it didn’t make starch without sunlight. This proves photosynthesis needs sunlight to produce food.
Question 12. What happens to a plant without water, and why is water important for growth?
Answer
Without water, a plant may wilt or die because water is essential for transporting nutrients and keeping the plant’s structure firm. Water is also needed for photosynthesis to make food (glucose). For example, the notes say a plant without water has fewer leaves and poor growth, while one with water grows tall with vibrant green leaves.
Question 13. Why are leaves called the “food factories” of plants? Give an example.
Answer
Leaves are called “food factories” because they make food (glucose) through photosynthesis using sunlight, chlorophyll, carbon dioxide, and water. Their broad, flat shape and chlorophyll help capture sunlight to produce starch. For example, the notes say an iodine test on a leaf exposed to sunlight turns blue-black, showing starch production, proving leaves make food for the plant.
Question 14. What are the other parts of plant where photosynthesis occurs except leaves?
Answer
While leaves are the primary site for photosynthesis, other green parts of the plant can also perform this process. These include:
- Green Stems: Some plants, like cacti and young stems of other plants, can carry out photosynthesis due to the presence of chlorophyll.
- Green Branches: Similar to stems, branches that have green tissues can also contribute to photosynthesis.
Question 15. What is chlorophyll?
Answer
Chlorophyll is a green pigment found in the leaves of all green plants. It plays an essential role in photosynthesis by capturing the energy from sunlight.
- This pigment absorbs light, especially sunlight, which is then used to convert carbon dioxide and water into glucose (a sugar) during photosynthesis.
- The presence of chlorophyll is also what gives plants their characteristic green colour.
Long Answer Questions
Question 1. Why do we boil the leaf in alcohol when we are testing it for starch?
Answer
In a starch test, we boil the leaf in alcohol to remove its chlorophyll, the green pigment that masks the presence of starch.
- When testing for starch in leaves, we need to see a colour change to confirm the presence of starch.
- After removing chlorophyll by boiling the leaf in alcohol, the leaf becomes pale.
- Once iodine solution is added, it reacts with the starch in the leaf, turning it blue-black.
- This confirms that starch is present, proving that photosynthesis has taken place.
Question 2. Define
(a) Parasites
(b) Total Parasites
(c) Partial Parasites
Answer
(a) Parasites: Parasites are organisms that live on or in a host organism and derive nutrients, often including food and shelter, at the host’s expense, causing harm.
Examples: Cuscuta (dodder), tapeworm, liver fluke. Parasites are classified as total or partial parasites based on their dependency.
(b) Total Parasites: The parasites that depend on the host for food and shelter are called total parasites.
Examples: liver fluke and tapeworm.
(c) Partial Parasites: Partial parasites are organisms, typically plants that can photosynthesize but depend on a host for water, nutrients, or support.
Examples: Mistletoe
Question 3. How does the plant use sunlight for photosynthesis?
Answer
- Sunlight is the energy source for photosynthesis.
- It is trapped by the green pigment chlorophyll in the leaves and all green parts of the plants.
- The chlorophyll is present in organelles called chloroplasts.
- Most of the chlorophyll is present in the leaves; therefore, leaves are the major site for trapping sunlight to convert it to chemical energy.
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| Chloroplasts contain Chlorophyll |
Question 4. Explain how photosynthesis occurs in plants.
Answer
Photosynthesis is a vital process that allows green plants to make their own food using sunlight.
How it works:
- Energy Source: Plants use solar energy (sunlight) to create food.
- Raw Materials: The two main ingredients needed for photosynthesis are:
1. Carbon Dioxide (CO₂): This gas comes from the air and is absorbed by the plant's leaves.
2. Water (H₂O): Plants take up water from the soil through their roots. - Role of Chlorophyll: The leaves of plants contain a green pigment called chlorophyll, which is essential for photosynthesis. Chlorophyll captures sunlight, providing the energy needed for the process.
- Chemical Reaction: Using the energy from sunlight, plants transform carbon dioxide and water into glucose (a type of sugar) and oxygen (O₂). The overall chemical reaction for photosynthesis can be summarized as:
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| Reaction of Photosynthesis |
- Products of Photosynthesis: The main product of photosynthesis is glucose, which serves as food for the plant. Oxygen is also produced and released into the atmosphere, which is essential for all living beings to breathe.
Question 5. How can we demonstrate that chlorophyll is necessary for photosynthesis?
Answer
Here’s a simple experiment to show that chlorophyll is necessary for photosynthesis:
Materials Needed:
- A potted plant with variegated leaves (green and non-green parts)
- Boiling water
- Ethanol (alcohol)
- Iodine solution
- Light source (sunlight or lamp)
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| Variegated Leaves |
Steps:
1. Prepare the Plant:- Take a variegated leaf from the plant.
- Keep the plant in the dark for 24 hours.
- Boil the leaf in water for 2-3 minutes to kill it.
- Place the boiled leaf in a beaker with ethanol and heat it in a hot water bath for 5-10 minutes. This removes chlorophyll and turns the leaf pale.
- Rinse the leaf in warm water, then soak it in iodine solution for a few minutes. Iodine will turn blue-black in the presence of starch.
- The green parts turn blue-black, indicating starch is present (photosynthesis occurred).
- The non-green parts stay yellow or brown, showing no starch (no photosynthesis).
Conclusion:
- The experiment shows that only the green parts of the leaf, which contain chlorophyll, can make food (starch) through photosynthesis. Non-green parts do not have chlorophyll and cannot perform photosynthesis.
Question 6. How do plants obtain nutrients other than carbohydrates?
Answer
Plants primarily produce carbohydrates through photosynthesis, using sunlight to convert carbon dioxide and water into starch. However, they obtain other essential nutrients directly from the soil. Here’s how this process works:
- Nutrient Absorption: Plants absorb nitrogen from the soil in the form of nitrates and ammonium.
- Role of Nitrogen-Fixing Bacteria: Nitrogen compounds in the soil are created by nitrogen-fixing bacteria, such as Rhizobium. These bacteria live in a symbiotic relationship with the roots of leguminous plants, helping to convert atmospheric nitrogen into forms that plants can use.
Rhizobium: Nitrogen Fixing Bacteria
- Replenishing Nutrients: Farmers can replenish nitrogen compounds in the soil by adding fertilizers and manure. These additions enrich the soil, providing essential nutrients for plant growth.
- Insectivorous Plants: Some plants, like the pitcher plant and Venus flytrap, obtain nitrogen by trapping and digesting insects. This process releases nutrients from the insects, which are then absorbed by the plant.
Question 7. What is the mode of nutrition in fungi?
Answer
- The mode of nutrition in fungi is heterotrophic.
- They cannot synthesize their food and depend on other ‘organisms’ for their carbon source.
- They perform extracellular digestion by releasing enzymes into their environment and obtaining organic and inorganic nutrients through absorption.
- Saprotrophic: Decomposition of ‘dead organic matter’.
- Parasitic: Feeding from a living host.
- Mutualism: Living in a mutually beneficial interaction with another organism. (Example: lichen is a mutualism between fungi and algae).
Question 8. Explain the process of photosynthesis in detail.
Answer
Photosynthesis is a process by which plants produce their own food. It takes place in the leaves, mainly in the chloroplasts, which contain chlorophyll. During photosynthesis, plants absorb sunlight through chlorophyll. The sunlight, along with water absorbed by the roots and carbon dioxide from the air (through stomata), reacts to produce glucose (a simple carbohydrate) and oxygen.
The word equation for photosynthesis is:
Carbon dioxide + Water → Glucose + Oxygen
Glucose is used by the plant as an immediate energy source or stored as starch for later use. Oxygen is released as a by-product, which is crucial for the survival of other organisms, including humans.
Question 9. How do plants transport water, minerals, and food within their structure?
Answer
Plants have a specialized transport system to move water, minerals, and food to different parts. Water and minerals are absorbed by the roots from the soil and transported upwards to the leaves through xylem tissue. The xylem acts like a pipeline, carrying water and minerals to the stems, leaves, and flowers.
Food produced during photosynthesis (mainly glucose) is transported through phloem, another type of vascular tissue. The phloem carries the food from the leaves, where it is made, to other parts of the plant like roots, stems, and fruits. These processes ensure that the plant gets the necessary nutrients for growth, energy, and reproduction.
Question 10. Describe the role of sunlight, water, and chlorophyll in plant growth and food production.
Answer
Sunlight, water, and chlorophyll are essential for plant growth and food production.
- Sunlight provides energy for photosynthesis. Chlorophyll absorbs sunlight and helps convert it into chemical energy.
- Water is necessary for transporting nutrients through the plant and helps maintain its structure. It also participates in photosynthesis by combining with carbon dioxide to form glucose.
- Chlorophyll, the green pigment in leaves, captures sunlight and enables plants to perform photosynthesis. Without chlorophyll, plants cannot produce food effectively, even if they have sunlight and water.
Question 11. What is respiration in plants, and how does it differ from photosynthesis?
Answer
Respiration in plants is a process where plants break down glucose (produced during photosynthesis) using oxygen to release energy.
The equation for respiration is:
Glucose + Oxygen → Carbon dioxide + Water + Energy
This energy is used for growth, repair, and other functions within the plant. Respiration occurs in all parts of the plant, both green and non-green.
In contrast, photosynthesis occurs only in the green parts of the plant (mainly the leaves), where sunlight, water, and carbon dioxide are used to produce glucose and oxygen. Unlike respiration, which releases energy, photosynthesis stores energy in the form of glucose.
Question 12. How do stomata function in gas exchange during photosynthesis and respiration?
Answer
Stomata are tiny pores located on the surface of leaves that play a key role in gas exchange. During photosynthesis, stomata allow carbon dioxide to enter the leaf from the air, which is necessary for the production of glucose. At the same time, oxygen, a by-product of photosynthesis, exits the leaf through the stomata.
In respiration, the stomata also allow oxygen to enter for the breakdown of glucose and the release of energy, while carbon dioxide, a waste product of respiration, exits the plant. The opening and closing of stomata are regulated by guard cells, ensuring that the plant can exchange gases efficiently while minimizing water loss.
Question 13. Where does the starch in potatoes come from? Where is the food synthesised in the plant, and how does it reach the potato?
Answer
The starch in potatoes comes from the food made in the leaves of the plant. The plant makes food in the form of glucose through a process called photosynthesis, which happens in the leaves when the plant takes in sunlight, carbon dioxide, and water.
Once the leaves make glucose, it travels through the plant to other parts, like the potato, through special tubes called phloem. The potato acts like a storage place where the glucose is turned into starch and stored for later use, which is why when you test a potato with iodine, you see a blue-black colour, showing the presence of starch.
Question 14. Describe how plants transport water and food, including the roles of xylem and phloem. Explain how respiration in plants differs from photosynthesis.
Answer
Transport of Water (Xylem):
- Xylem is a tissue with tube-like structures that carries water and minerals from roots to stems, leaves, and flowers.
- Roots absorb water and minerals from soil, and xylem moves them upward to support photosynthesis and keep plants firm.
- Example: In the coloured water experiment, a twig in red water shows colour moving up the stem to leaves, proving xylem transports water.
Transport of Food (Phloem):
- Phloem is a tissue that carries food (glucose or starch) made in leaves to non-green parts like roots, stems, and fruits for growth and storage.
- Example: Glucose made in leaves reaches developing fruits, helping them grow, like apples getting sweeter.
Respiration and Photosynthesis:
- Respiration: Plants break down glucose using oxygen in all parts (green or non-green) to release energy, carbon dioxide, and water. This energy helps growth and nutrient transport.
- Photosynthesis: Leaves use sunlight, carbon dioxide, and water to make glucose and oxygen, only in green parts with chlorophyll.
Difference: Photosynthesis makes food in sunlight, while respiration uses that food for energy anytime, producing opposite gases (oxygen out in photosynthesis, carbon dioxide out in respiration).