Question

1. How do you suppose heterotrophic bacteria that are incapable of secreting hydrolytic enzymes are able to use such food as starch.

2. How is the supply of oxygen normally maintained in the seas?

3. What are the two major groups of autotrophic bacteria? The two groups use different energy sources in order to manufacture organic compounds from inorganic compounds, but the carbon source for both group is_____.

Answer 1

1.  More complex carbohydrates like starch or cellulose take a bit more effort, as they need to be broken down into their component simple sugars before they can be processed. To break them down bacteria use a specific group of enzymes called CAZymes which stands for “carbohydrate-active enzymes". As enzymes are very specialised in the molecules that they break down, different CAZymes exist for different complex carbohydrates.

2. The surface water is usually saturated with oxygen, absorbed from the atmosphere and from the photosynthesis of algae. In the deepwater, the oxygen is consumed when breaking down the organic matter that sinks from the surface. The only oxygen supply in deep water is either the addition of new water or vertical mixing.

3. There are two types of autotrophs: photoautotrophs and chemoautotrophs. Photoautotrophs get their energy from sunlight and convert it into usable energy (sugar). This process is called photosynthesis. Chemoautotrophs are cells that create their own energy and biological materials from inorganic chemicals. Carbon source of both groups is carbon dioxide.