Question

State if the following statements are true or false. Correct the false statements
A. Photosynthesis and respiration take place all the time in plants.
B. For respiration sunlight and chlorophyll are needed.
C. In old stems, gaseous exchange takes place through the stomata.
D. Photosynthesis occurs only in chlorophyll containing plants.
E. Respiration which requires oxygen is known as anaerobic respiration.
F. Aerobic respiration takes place in the absence of oxygen.

Answer 1

Hint: Photosynthesis is the process of conversion of carbon dioxide and water into oxygen and carbohydrates (sugars) using light energy source by plants. Green plants and certain other organisms with chlorophyll convert light energy to chemical energy. Respiration is required for the growth of the plant.

Complete answer:
Photosynthesis and respiration take place all the time in plants: This statement is not entirely true. Although respiration in plants occurs all the time, photosynthesis only occurs in the presence of sunlight. As discussed earlier, photosynthesis is the conversion of light energy into chemical energy. The sugars produced during photosynthesis including the oxygen produced are utilized to produce energy for growth in plants, this is the process involved in respiration.
-For respiration sunlight and chlorophyll are needed: Plants require energy and this is obtained through the process of respiration. Respiration occurs in the presence of oxygen to form water and carbon dioxide to breakdown glucose and release energy. Respiration does not require sunlight and chlorophyll, photosynthesis requires these. Therefore this statement is false.
-In old stems, gaseous exchange takes place through the stomata: Stomata are minute pores present in leaves. These pores diffuse atmospheric gases and transfer them to different parts of the plant. Stems also receive diffused gases through stomata. Therefore, this statement is true.
-Photosynthesis occurs only in chlorophyll-containing plants: Chlorophyll is a pigment that participates in the process of photosynthesis by absorbing light. Chlorophyll is of two main types: chlorophyll A and chlorophyll B. Chlorophyll has the ability to absorb light energy from different wavelengths of orange-red light and violet-blue. It appears to impart green colours in plants because it can reflect green-yellow light. Chlorophyll A acts as an electron donor in the electron transport chain. Chlorophyll B functions to absorb high-frequency blue light which is utilized in photosynthesis. Therefore, this statement is true.
-Respiration which requires oxygen is known as anaerobic respiration: Anaerobic respiration takes place within the cytoplasm of prokaryotes such as bacteria and yeast. They occur in the absence of oxygen, liberating less amount of energy. Therefore this statement is false.
-Aerobic respiration takes place in the absence of oxygen: Aerobic respiration takes place in the presence of oxygen in the mitochondria of all eukaryotic entities. This type of respiration is observed in higher forms of life and oxidises food molecules completely with the release of energy. Therefore, this statement is false.

Note: Chlorophylls are of four types: Chlorophyll A, Chlorophyll B, Chlorophyll C, and Chlorophyll D. Chlorophyll A is present in all higher plants, cyanobacteria and algae; Chlorophyll B is present in green algae and higher plants; Chlorophyll C is located in dinoflagellates, brown algae and diatoms; Chlorophyll D is found only in red algae.