Answer:
1. A
2. C
3. B
4. A
Explanation:
1. The rate of gas exchange is higher at the shallow zones this is because the water in this zone has 100% saturated i.e it contains as many air molecules in water as in air. Therefore, species prefer to live in the shallow zone.
Hence, option A is correct
2. Cyanobacteria need sunlight for photosynthesis for producing food for itself and other organisms. Since sunlight cannot reach greater ocean depths, hence the cyanobacteria will not photosynthesize and die eventually.
Thus, option C is correct
3. At greater depths oxygen concentration increases, therefore there are high chances that a species which lives at greater depth may require higher percentage of oxygen. Since the observation of the scientist is exactly opposite to the established concept hence, he might be using wrong data set.
Option B is correct
4. During freezing temperatures, the water as ice floats on the top of the surface thereby allowing water below it to expand more than the normal scenario thereby entrapping more oxygen and hence allowing organisms to breathe. Thus, option A is correct
