Class 7A Homework
Date-20/04/21
Short answer questions:-
1.What is Symbiosis? 2.How does exchange of gases takes place in leaves? 3.What is Photosynthesis? 4.What is the first step in Photosynthesis? 5.What are total and partial parasites? Give examples. 6.What is the importance of photosynthesis? 7.With the help of an activity prove that chlorophyll is essential for photosynthesis. 8.How would you demonstrate that light is necessary for photosynthesis?
Answers
Answer:
1. What is Symbiosis?
The living together in more or less intimate association or close union of two dissimilar organisms especially : mutualism.
2. How does exchange of gases takes place in leaves?
The exchange of oxygen and carbon dioxide in the leaf (as well as the loss of water vapor in transpiration) occurs through pores called stomata (singular = stoma). Normally stomata open when the light strikes the leaf in the morning and close during the night.
3. What is Photosynthesis?
Photosynthesis is a process by which autotrophs convert light energy into chemical energy, which is later used to fuel cellular activities. The chemical energy is stored in the form of sugars, which are created from water and carbon dioxide.
4. What is the first step in Photosynthesis?
The first step in photosynthesis is the light reaction or photochemical reactions resulting in the formation of ATP and NADPH, which are later utilised in the biosynthesis process.
5. What are total and partial parasites? Give examples.
Total parasite plants are heterotrophic plants that depend entirely on the host plant, including shelter, water, food, for all their requirements. Examples: Orobanche aegyptiaca, cuscuta reflexa and striga asiatica. Partial parasites are those that rely, in portion, on their hosts.
6. What is the importance of photosynthesis?
It's not oxygen production. The primary function of photosynthesis is to convert solar energy into chemical energy and then store that chemical energy for future use. For the most part, the planet's living systems are powered by this process.
7. With the help of an activity prove that chlorophyll is essential for photosynthesis.
Take a variegated leaf of the potted plant kept in bright sunlight. Trace the outline of leaves and its variegated parts on the tracing paper (the variegated leaves show pale yellow spots in green leaves. These areas indicate the absence of chlorophyll). ... Thus, the chlorophyll is essential for photosynthesis.
8. How would you demonstrate that light is necessary for photosynthesis?
Light is one of the requirements for photosynthesis. When a part of the leaf is covered from both upper and lower sides with a black paper strip, light will not reach to covered part. ... Presence of starch in the leaf, which can be detected by performing iodine test, indicates occurrence of photosynthesis.