Test: Nutrition in Plants- 3 - Class 7 MCQ

- P - Carbon dioxide is essential for photosynthesis to take place.
- This statement is true. Carbon dioxide is one of the reactants needed for photosynthesis to occur in plants.

- Q - The products of photosynthesis are simple sugars.
- This statement is true. The main products of photosynthesis are simple sugars, such as glucose, that provide energy for the plant.

- R - Photosynthesis occurs in the green leaves of plants.
- This statement is true. Photosynthesis primarily takes place in the chloroplasts of the green leaves of plants, where chlorophyll captures sunlight energy.

- S - Sunlight is not used as an energy source by plants to make food during photosynthesis.
- This statement is false. Sunlight is a crucial energy source for plants during photosynthesis. It is absorbed by chlorophyll and used to convert carbon dioxide and water into glucose and oxygen.

So option D is correct

In the given equation X represents carbon dioxide and Y represents oxygen.

During photosynthesis, solar energy is converted into chemical energy. This process takes place in the chloroplasts of plant cells and involves several steps. Here is a detailed explanation:
1. Light Absorption:
- Chlorophyll, a pigment found in chloroplasts, absorbs sunlight.
- The energy from the sunlight is used to excite electrons in the chlorophyll molecules.
2. Light-dependent Reactions:
- Excited electrons are transferred through a series of proteins called the electron transport chain.
- This chain generates ATP (adenosine triphosphate), a molecule that stores energy.
- Water molecules are split, releasing oxygen as a byproduct.
- The electrons from the water molecules replace the excited electrons in the chlorophyll molecules.
3. Calvin Cycle (Light-independent Reactions):
- ATP and the excited electrons produced in the light-dependent reactions are used in the Calvin cycle.
- Carbon dioxide from the atmosphere enters the cycle and combines with the electrons to form glucose.
- Glucose is a carbohydrate that stores chemical energy.
4. Energy Storage:
- Glucose molecules produced during photosynthesis can be used for various purposes in plants.
- They can be stored as starch or converted into other organic molecules.
- The chemical energy stored in glucose can be used for growth, reproduction, or as a source of energy for cellular respiration.
In conclusion, during photosynthesis, solar energy is converted into chemical energy in the form of glucose. This process is essential for plants to produce their own food and release oxygen into the atmosphere.

Symbiosis is a mutually beneficial relationship between two organisms.

• Light from the sun is the primary energy source for biological systems.
• Plants capture sunlight through photosynthesis, converting it into chemical energy stored in carbohydrates.
• These carbohydrates serve as food for other organisms, creating a food chain.
• Thus, all life ultimately relies on solar energy, making it the foundation of energy input in ecosystems.

Most CO₂ reach the photosynthesising cells of green leaves through diffusion. Stomata (tiny pores) present of leaf surface and stem facilitates gaseous exchange between the plant cells and the surrounding. CO₂ move into the cells through these small pores.

Algae are the small green plants, which appears as slimy and green patches in ponds or in stagnant water.

So option D is correct

Fertilisers and manures are essential for maintaining soil health because they replenish the nutrients in the soil that plants absorb as they grow. Over time, as crops are harvested and plants take up nutrients, the soil can become depleted of essential elements like nitrogen, phosphorus, and potassium. Fertilisers and manures help to restore these nutrients, ensuring that the soil remains fertile and can continue to support healthy plant growth.

- Photosynthesis is the process by which plants convert light energy into chemical energy.
- Light intensity is a critical factor; as it decreases, the energy available for photosynthesis also reduces.
- With less light, plants cannot produce glucose efficiently, leading to a reduction in the overall rate of photosynthesis.
- At very low light levels, photosynthesis may slow down significantly or nearly stop, but it does not completely cease until light is absent.

Insectivorous plants trap insects to obtain nutrients, especially nitrogen, from the insects, which are often scarce in their native soils.