Identify the correct sequence of changes in modes of nutrition in organism after origin of life on earth:
(a) Non oxygenic photosynthesis
(b) Chemoheterotrophs
(c) Oxygenic photosynthesis
(d) Chemoautorophs

Options

A. (b), (a), (c), (d)
B. (d), (b), (c), (a)
C. (d), (c), (a), (b)
D. (b), (d), (a), (c)

Answer

To identify the correct sequence of changes in modes of nutrition in organisms after the origin of life on Earth, we can analyze the types of nutrition mentioned in the question:

1. **Chemoheterotrophs**: These organisms obtain their energy by consuming organic compounds. They do not produce their own food and rely on other organisms for nutrition. This mode of nutrition is believed to be one of the earliest forms of life, as primitive life forms would have relied on available organic materials.

2. **Chemoautotrophs**: These organisms can synthesize their own food using inorganic substances. They derive energy from chemical reactions involving inorganic molecules, such as hydrogen sulfide or ammonia. This mode of nutrition likely evolved after chemoheterotrophs, as it allowed organisms to exploit a wider range of environments.

3. **Non-oxygenic photosynthesis**: This process involves organisms that can perform photosynthesis without producing oxygen, typically using substances like hydrogen sulfide as an electron donor. This mode of nutrition would have emerged as organisms began to harness light energy for food production.

4. **Oxygenic photosynthesis**: This is the process used by plants and cyanobacteria, where sunlight is used to convert carbon dioxide and water into glucose and oxygen. This mode of nutrition represents a significant evolutionary advancement, as it led to the production of oxygen as a byproduct, which dramatically changed the Earth's atmosphere.

Now, putting these modes of nutrition in the correct chronological order after the origin of life, we have:

1. **Chemoheterotrophs** (first)
2. **Chemoautotrophs** (second)
3. **Non-oxygenic photosynthesis** (third)
4. **Oxygenic photosynthesis** (fourth)

Thus, the correct sequence is:
- (b) Chemoheterotrophs
- (d) Chemoautotrophs
- (a) Non-oxygenic photosynthesis
- (c) Oxygenic photosynthesis

### Final Answer:
The correct sequence of changes in modes of nutrition after the origin of life on Earth is:
1. Chemoheterotrophs
2. Chemoautotrophs
3. Non-oxygenic photosynthesis
4. Oxygenic photosynthesis