Short & Long Types Questions: Nutrition in Plants

Short Type Questions Answers 

Ans: Autotrophic nutrition is the process by which an organism makes its own food from simple inorganic substances such as water and carbon dioxide, using an external energy source (usually sunlight). Plants that carry out this process are called autotrophs; they use chlorophyll to capture light energy and convert it into chemical energy in the form of glucose.

Q.2. What is photosynthesis?

Ans: Photosynthesis is the process by which green plants and some other organisms use light energy, water and carbon dioxide to produce glucose (a form of sugar) and oxygen. This process takes place mainly in the chloroplasts of leaf cells where chlorophyll absorbs light energy to drive the reaction.

Q.3. What is heterotrophic nutrition?

Ans: Heterotrophic nutrition is the mode of nutrition in which organisms obtain food by consuming other organisms or organic matter. Heterotrophs cannot make their own food and include animals, fungi and many bacteria and some plants.

Q.4 What is nutrition?

Ans: Nutrition is the process by which organisms take in food and use it to obtain energy and the raw materials needed for growth, repair and other life processes. It includes steps such as intake, digestion, absorption and utilisation of nutrients, and removal of undigested waste.

Q.5. What is the difference between parasitic and saprophytic plants?

Ans: Parasitic and saprophytic plants differ as follows:
a. Parasitic plants obtain nutrients from living host plants by attaching to them and drawing water and food. They often use specialised structures called haustoria to penetrate the host's tissues. Example: Cuscuta (dodder).
b. Saprophytic plants obtain nutrients from dead and decaying organic matter. They secrete enzymes to break down complex dead material into simpler substances which they then absorb. Example: Indian Pipe.

Long Type Questions Answers

Q.1. What is the importance of photosynthesis in plants? How does it contribute to the ecosystem?

Ans: Photosynthesis is vital for plants and for the whole ecosystem. Its importance and contributions are:
1. Source of food: Photosynthesis produces glucose which is used by plants for energy, growth and as building material (for example, to make starch and cellulose). Plants form the base of most food chains, so their food supports herbivores and, in turn, carnivores.
2. Oxygen production: Oxygen released during photosynthesis is essential for respiration by animals, plants and many microbes.
3. Carbon dioxide balance: Plants remove carbon dioxide from the atmosphere during photosynthesis, helping to regulate greenhouse gases and maintain atmospheric balance.
4. Supports ecosystems: By producing biomass, plants supply energy and nutrients that sustain ecosystems, including soil organisms and decomposers.
5. Raw materials and fuels: Plant products are used by humans for food, fibres, timber and fuels; much of this originates from photosynthetic activity.

Q.2.   Explain the process of nutrient absorption in plants. How do plants obtain nutrients from the soil?

Ans: Plants absorb nutrients from the soil mainly through their roots. The process can be understood in these points:
1. Root hairs: Tiny extensions of root epidermal cells called root hairs increase the surface area in contact with soil and absorb water and dissolved mineral ions.
2. Movement of water and ions: Water moves into root hairs by osmosis. Mineral ions move by diffusion or are taken up by active transport when their concentration in soil is lower than in root cells.
3. Role of mycorrhizae: Many plants form symbiotic associations with fungi called mycorrhizae. These fungi increase the effective surface area for absorption and help dissolve and supply minerals to the plant.
4. Transport inside the plant: Absorbed water and minerals travel through the root into the xylem vessels and are carried to stems and leaves where they are used in growth and photosynthesis.

Q.3. What are the necessary conditions for photosynthesis to occur? Explain each condition briefly.

Ans: Photosynthesis requires a few essential conditions:
a. Light: Light energy (usually sunlight) is needed to drive the reactions. Chlorophyll absorbs this light energy.
b. Chlorophyll: This green pigment, present in chloroplasts, captures light energy and starts the process.
c. Carbon dioxide: CO₂ from air is used as the carbon source to make glucose. Leaves take CO₂ in through small openings called stomata.
d. Water: Water absorbed by roots supplies hydrogen and electrons needed in the light-dependent steps and keeps leaf cells turgid.
e. Temperature: Temperature affects the rate of the enzyme-controlled reactions. For many common plants, an optimum range is about 20-25°C; lower or higher temperatures reduce the rate.

Q.4.  Describe autotrophic nutrition in detail. Provide an example of an autotrophic plant and explain how it obtains its food.

Ans: Autotrophic nutrition is when an organism makes its own food from simple inorganic substances. In green plants this happens by photosynthesis. Key points:
1. Site: Photosynthesis occurs mainly in the leaves, inside cell structures called chloroplasts which contain chlorophyll.
2. Raw materials: Water is absorbed by roots and carbon dioxide by leaves through stomata. Light energy is captured by chlorophyll.
3. Process: Light energy is used to convert water and carbon dioxide into glucose. Oxygen is released as a by-product.
4. Use of glucose: Glucose is used immediately for energy, for making other compounds, or stored as starch for later use.
Example: A typical green plant such as a neem or pea plant obtains water from soil through roots, takes in carbon dioxide from air, captures sunlight with chlorophyll in leaves, and produces its food by photosynthesis.

Q.5. Explain the different types of heterotrophic plants.

Ans: Heterotrophic plants obtain food from other organisms or dead matter. Main types are:
1. Parasitic plants: These live on or in another living plant (the host) and take water and nutrients from it, often using haustoria to penetrate host tissues. Example: Cuscuta (dodder), mistletoe.
2. Saprophytic plants: These feed on dead and decaying organic matter. They secrete enzymes to break down complex material into simpler substances and then absorb them. Example: Indian Pipe.
3. Insectivorous plants: These trap and digest insects to obtain nutrients (especially nitrogen) that are scarce in their soil. Trapping methods include sticky surfaces, snap traps and pitfall traps. Example: Venus Flytrap, Pitcher Plant.
4. Symbiotic plants: These live in a mutually beneficial relationship with other organisms (often fungi). The partner provides mineral nutrients or helps absorb them, while the plant supplies carbohydrates. Example: Many plants form mycorrhizal associations with fungi; both partners benefit.