Two green plants are kept separately in oxygen free containers, one in the dark and other in sunlight. It was observed that plant kept in dark could not survive longer. Give reason for this observation.
Two green plants are kept separately in oxygen free containers, one in the dark and other in sunlight. It was observed that plant kept in dark could not survive longer. Give reason for this observation.
The plant kept in sunlight survives longer because it can perform photosynthesis. During photosynthesis, it absorbs light energy and converts it into chemical energy, splitting water molecules to release oxygen () as a by-product:
This released oxygen is then utilized by the plant for respiration (the breakdown of food sources for cellular energy needs).
Conversely, the plant kept in the dark cannot perform photosynthesis due to the absence of sunlight. Therefore, it cannot produce oxygen. Since the container is oxygen-free, the plant in the dark cannot carry out respiration to maintain its life processes, leading to its early death.
Marking Scheme
- 1State that the plant in sunlight performs photosynthesis, releasing oxygen (), which is used for its respiration. (1 mark)
- 2State that the plant in the dark cannot perform photosynthesis due to lack of sunlight, leading to oxygen deprivation and failure of respiration. (1 mark)
Hint
Think about which plant can produce its own oxygen using sunlight, and why oxygen is necessary for the survival of both plants in closed containers.
Quick Oral Answer
The plant in sunlight survives because it performs photosynthesis to produce oxygen, which it then uses to breathe (respire). The plant in the dark cannot make oxygen without sunlight, so it suffocates in the oxygen-free container.
Analysis & Explanation
This question tests the conceptual link between photosynthesis and respiration in plants. While plants release oxygen during photosynthesis, they also require oxygen for respiration to break down stored carbohydrates and generate energy for maintenance processes. In an airtight, oxygen-free container, the only source of oxygen is the plant's own photosynthetic activity. Since photosynthesis requires sunlight, only the plant in the light can generate the oxygen necessary to sustain its respiration. The plant in the dark is deprived of both light (for photosynthesis) and oxygen (for respiration), causing its maintenance systems to break down quickly.
Common Mistakes
- 1Assuming plants only breathe out carbon dioxide and do not require oxygen for respiration.
- 2Forgetting to mention that sunlight is the essential driving factor for the oxygen-producing step of photosynthesis.
Interesting Facts
During the day, the rate of photosynthesis is much higher than the rate of respiration, meaning plants produce far more oxygen than they consume!
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2023?
This question carries 2 marks in the CBSE Class 10 Science 2023 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Life Processes" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Photosynthesis and Respiration" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2023 paper?
This is a Very Short Answer question from Section B in the CBSE Class 10 Science 2023 paper.