Test: Photosynthesis and Respiration - Class 7 MCQ

Nitrogen is not directly involved in the photosynthetic process. The primary requirements for photosynthesis are sunlight, water, and carbon dioxide, which are utilized by plants to produce glucose and oxygen. Nitrogen is important for plant growth but does not play a role in photosynthesis itself.

Excessive temperature can limit the rate of photosynthesis, especially if it exceeds 40°C, as it may damage the enzymes involved in the process. Photosynthesis requires optimal conditions, and deviations can hinder its efficiency.

Photosynthesis is essential for life on Earth because it generates oxygen, which is crucial for the respiration of almost all living organisms. Moreover, it is the foundation of the food chain, providing energy for autotrophs and, indirectly, for heterotrophs.

Xylem is responsible for transporting water and minerals from the roots to the leaves, which are essential for photosynthesis. Phloem, on the other hand, transports the glucose produced in the leaves to other parts of the plant for use or storage.

Mesophyll cells in leaves contain numerous chloroplasts, which are essential for photosynthesis. These cells are located between the upper and lower epidermis of the leaf and are structured to maximize light absorption and gas exchange.

Guard cells surround stomata and control their opening and closing, thus regulating gas exchange. When guard cells absorb water, they swell and open the stomata, allowing carbon dioxide in and oxygen out, which is essential for photosynthesis.

The main product of photosynthesis is glucose, which serves as an energy source for the plant. Oxygen is a byproduct released during the process, but glucose is the essential product that plants use for growth and energy.

Chlorophyll plays a crucial role in photosynthesis by absorbing sunlight, which provides the energy necessary for the conversion of carbon dioxide and water into glucose and oxygen. Without chlorophyll, the process of photosynthesis would not occur effectively, as it is the pigment that captures light energy.

The primary byproduct of photosynthesis is oxygen. While glucose is the main product utilized by the plant, oxygen is released into the atmosphere through the stomata, which is crucial for the respiration of many living organisms.

The energy currency produced during cellular respiration is ATP (Adenosine Triphosphate). ATP stores energy that can be used for various cellular functions, making it vital for the survival and functioning of all living organisms.

The term "autotroph" refers to organisms, such as green plants, that produce their own food through processes like photosynthesis. They use sunlight, water, and carbon dioxide to create energy-rich compounds, distinguishing them from heterotrophs, which rely on consuming other organisms.

Glucose produced during photosynthesis can be used immediately for energy by the plant cells or converted and stored as insoluble starch for later use. This flexibility allows plants to manage their energy needs effectively.

In cellular respiration, oxygen acts as a reactant that allows glucose to be fully oxidized, releasing energy stored in its bonds. This energy is then captured in the form of ATP, which is essential for various cellular activities.

Aerobic respiration requires oxygen to fully oxidize glucose, producing carbon dioxide, water, and a significant amount of ATP. In contrast, anaerobic respiration occurs without oxygen and results in less ATP production and partial breakdown of glucose.

During anaerobic respiration in plants, glucose is partially broken down into ethanol and carbon dioxide, generating less energy compared to aerobic respiration. This process occurs in environments where oxygen is scarce.

Increased light intensity can enhance the rate of photosynthesis, as it provides more energy for the process. However, it's important to note that the increase in light must be within optimal conditions; excessive light can damage chlorophyll and hinder the process.

The oxygen produced during photosynthesis is released into the atmosphere through stomata. This released oxygen is vital for the respiration of animals and other organisms, thus playing a critical role in maintaining life on Earth.

Glucose is significant for plants as it provides energy for growth, development, and metabolic processes. Additionally, it can be stored as starch for future use, ensuring that the plant has energy reserves during periods of low photosynthesis.

Photosynthesis primarily occurs in the leaves, specifically within the mesophyll cells that contain chloroplasts. The structure of leaves, with their broad surfaces and high chlorophyll content, allows for optimal light absorption necessary for this process.

Stomata are small openings on the leaf surface that regulate gas exchange. They allow carbon dioxide to enter for photosynthesis and oxygen to be released as a byproduct. The opening and closing of stomata are controlled by guard cells, which respond to environmental conditions.