Exercise Questions and Answers
- Why do organisms take food?
- Organisms take food to obtain the necessary nutrients required for growth, energy, repair of damaged parts, and for carrying out vital life processes.
- Distinguish between a parasite and a saprotroph.
- Parasite: A parasitic plant like Cuscuta takes food from a living host plant, harming the host in the process.
- Saprotroph: A saprotrophic organism like fungi obtains its nutrients from dead and decaying organic matter. They do not harm living organisms.
- How would you test the presence of starch in leaves?
- To test for starch in leaves, follow these steps:
- Boil the leaf in water to soften it.
- Heat the leaf in iodine solution.
- If starch is present, the iodine will turn the leaf a blue-black color.
- To test for starch in leaves, follow these steps:
- Give a brief description of the process of synthesis of food in green plants.
- Green plants synthesize their own food through the process of photosynthesis. In the presence of sunlight, chlorophyll in the leaves absorbs light energy, which is used to combine carbon dioxide from the air and water from the soil to produce glucose (carbohydrate) and oxygen. The equation is: Carbon dioxide+Water→Sunlight, ChlorophyllGlucose+Oxygen\text{Carbon dioxide} + \text{Water} \xrightarrow{\text{Sunlight, Chlorophyll}} \text{Glucose} + \text{Oxygen}
- Show with the help of a sketch that plants are the ultimate source of food.
- (You can draw a simple diagram showing a plant producing food through photosynthesis, with arrows showing how animals (herbivores) eat plants and then carnivores eat herbivores, illustrating the food chain.)
- Fill in the blanks: (a) Green plants are called autotrophs since they synthesise their own food.
(b) The food synthesised by plants is stored as starch.
(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.
(d) During photosynthesis, plants take in carbon dioxide and release oxygen gas. - Name the following: (i) A parasitic plant with yellow, slender, and branched stem: Cuscuta (Amarbel).
(ii) A plant that is partially autotrophic: Pitcher plant (feeds on insects but also carries out photosynthesis).
(iii) The pores through which leaves exchange gases: Stomata. - Tick the correct answer: (a) Cuscuta is an example of:
(ii) parasite
(b) The plant which traps and feeds on insects is:
(iv) pitcher plant - Match the items given in Column I with those in Column II:
Column I Column II Chlorophyll Leaf Nitrogen Rhizobium Cuscuta Parasite Animals Heterotrophs Insects Pitcher plant - Mark ‘T’ if the statement is true and ‘F’ if it is false: (i) Carbon dioxide is released during photosynthesis. (F)
(ii) Plants which synthesise their food are called saprotrophs. (F)
(iii) The product of photosynthesis is not a protein. (T)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T) - Choose the correct option from the following: Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(ii) Stomata - Choose the correct option from the following: Plants take carbon dioxide from the atmosphere mainly through their:
(iv) leaves - Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?
- Farmers grow crops in greenhouses to regulate the amount of light, water, and carbon dioxide available to the plants, providing optimal growing conditions. This controlled environment helps plants grow more efficiently, leading to better yields and faster growth.
Extended Learning — Activities and Projects:
- Project:
- (Explanation of experiment to test photosynthesis by covering part of leaves with black paper, keeping the plant in sunlight, and then performing the iodine test.)
- Visit a greenhouse:
- (Visit a greenhouse to observe how light, water, and carbon dioxide are regulated. Report findings on how these factors influence plant growth.)
- Growing a Sweet Potato:
- (Experiment to grow a sweet potato in water and observe root and stem growth. Describe the changes over time.)
Nutrition in Plants along with their answers.
1. What is nutrition?
Answer: Nutrition is the process by which living organisms take in and utilize food to grow, repair, and obtain energy.
2. What are nutrients?
Answer: Nutrients are components of food that are necessary for the body to function properly. They include carbohydrates, proteins, fats, vitamins, and minerals.
3. What is the difference between autotrophic and heterotrophic nutrition?
Answer: Autotrophic nutrition is when organisms make their own food from simple substances (like plants do with sunlight), while heterotrophic nutrition is when organisms depend on other organisms for food (like animals).
4. Why are plants called autotrophs?
Answer: Plants are called autotrophs because they can make their own food using carbon dioxide, water, and sunlight.
5. What is the mode of nutrition in humans and animals?
Answer: Humans and animals have a heterotrophic mode of nutrition, meaning they depend on plants or other animals for food.
6. How do plants obtain the raw materials for photosynthesis?
Answer: Plants obtain raw materials like water and minerals from the soil through their roots and carbon dioxide from the air through the stomata in their leaves.
7. What is the function of the roots in plants?
Answer: The roots absorb water and minerals from the soil and transport them to other parts of the plant.
8. What are stomata?
Answer: Stomata are tiny pores found on the surface of leaves that allow the exchange of gases (carbon dioxide and oxygen) between the plant and the environment.
9. How does water and minerals reach the leaves from the roots?
Answer: Water and minerals are transported from the roots to the leaves through vessels that act like pipes, forming a continuous path throughout the plant.
10. What role does chlorophyll play in photosynthesis?
Answer: Chlorophyll is a green pigment in the leaves that captures sunlight and helps in synthesizing food by combining carbon dioxide and water during photosynthesis.
11. What is photosynthesis?
Answer: Photosynthesis is the process in which plants use sunlight, chlorophyll, water, and carbon dioxide to synthesize carbohydrates (food) and release oxygen.
12. Why is sunlight necessary for photosynthesis?
Answer: Sunlight provides the energy needed for plants to convert carbon dioxide and water into food (carbohydrates) through the process of photosynthesis.
13. What does the equation for photosynthesis represent?
Answer: The equation for photosynthesis is:
Carbon dioxide + Water + Light energy → Carbohydrate + Oxygen
It represents the process by which plants make food.
14. How do plants prepare food without chlorophyll?
Answer: Plants without chlorophyll (like parasitic plants) cannot make food through photosynthesis. They obtain nutrients from other plants or organic matter.
15. What is the significance of oxygen in photosynthesis?
Answer: Oxygen is released during photosynthesis and is essential for the survival of all living organisms that need it for respiration.
16. How do desert plants adapt to reduce water loss during photosynthesis?
Answer: Desert plants have modified leaves (such as spines) to reduce water loss and carry out photosynthesis in green stems.
17. What happens if plants do not perform photosynthesis?
Answer: If plants do not perform photosynthesis, there would be no food produced, and the survival of most living organisms would be impossible.
18. Why are some leaves red, violet, or brown in color?
Answer: Some leaves have pigments other than chlorophyll, which mask the green color but still allow the process of photosynthesis to occur.
19. What are algae?
Answer: Algae are simple, green organisms that live in water and can perform photosynthesis to produce food.
20. What is the main carbohydrate that plants produce during photosynthesis?
Answer: The main carbohydrate produced during photosynthesis is starch.
21. What is the role of nitrogen in plant nutrition?
Answer: Nitrogen is an essential nutrient for plants and is used to synthesize proteins. Plants absorb nitrogen in a usable form from the soil, often through the action of bacteria.
22. How do plants obtain nitrogen?
Answer: Plants obtain nitrogen from the soil, where it is converted from atmospheric nitrogen into a usable form by soil bacteria like Rhizobium.
23. What is Rhizobium?
Answer: Rhizobium is a bacterium that helps in converting atmospheric nitrogen into a form that plants can absorb and use for growth.
24. What is the parasitic mode of nutrition?
Answer: The parasitic mode of nutrition is when a plant (like Cuscuta) derives its food from another plant, known as the host, without giving anything back.
25. What are insectivorous plants?
Answer: Insectivorous plants are plants that trap and digest insects to obtain nutrients, as they may not get enough nutrients from the soil.
26. Why do insectivorous plants feed on insects?
Answer: Insectivorous plants feed on insects because they live in nutrient-poor soil and obtain essential nutrients like nitrogen from the insects they digest.
27. What is saprotrophic nutrition?
Answer: Saprotrophic nutrition is when organisms, like fungi, absorb nutrients from decaying organic matter.
28. How do fungi obtain nutrients?
Answer: Fungi absorb nutrients from dead and decaying organic matter through the process of saprotrophic nutrition.
29. What is symbiosis?
Answer: Symbiosis is a relationship between two organisms in which they live together and share both shelter and nutrients, such as the relationship between plants and Rhizobium bacteria.
30. Why do farmers add fertilizers to the soil?
Answer: Farmers add fertilizers to the soil to replenish the nutrients, like nitrogen, that plants need for healthy growth, as these nutrients are often depleted after each crop cycle.
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