Biology
Give the biological reasons for the following statements:
(i) It is advisable to keep green plants in an aquarium.
(ii) Water pollution is a major cause of concern in our country.
(iii) We cannot distinguish colours in dim light.
(iv) Medical discoveries such as antibiotics and vaccinations have indirectly contributed to the sharp rise in human population.
(v) Homo sapiens sapiens is the most highly evolved form of man.
Photosynthesis
ICSE 2020
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Answer
(i) Green plants release oxygen which dissolves in the water. This oxygen is used by fish in the aquarium. Therefore, to maintain the oxygen level in the water it is advisable to keep green plants in an aquarium.
(ii) India has the world's largest population but has only 4% of the world's freshwater resources. Pollution of water bodies, such as rivers, lakes, and groundwater is rapidly depleting these limited reserves leading to an acute shortage of clean water for domestic, agricultural, and industrial use.
(iii) We cannot distinguish colours in dim light because the cone cells, responsible for vision of colours are sensitive only to bright light.
(iv) Medical discoveries such as antibiotics and vaccinations have lowered death rate by treatment and prevention of deadly diseases, thus, indirectly contributing to the sharp rise in human population.
(v) Homo sapiens sapiens is the most highly evolved form of man as they possess the following main characteristics:
- Bipedal locomotion.
- Cranial capacity ranging from 1450 to 1600 cm3 and a much enlarged cerebrum.
- Prominent chin, snout disappeared.
- Highly reduced body hair.
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