Which of the following organisms is unicellular?

Here are the solutions to the questions:

1. The breakdown of food substances into simple, soluble and absorbable form is D. digestion. Digestion is the process by which complex food molecules are broken down into simpler, absorbable forms.

2. An association between two organisms in which one benefits without causing harm to the other is A. commensalism. In commensalism, one organism benefits, and the other is neither helped nor harmed.

3. The food substance that gives the highest amount of calories is D. groundnut. Groundnuts are rich in fats and proteins, which provide a high amount of energy (calories) per unit mass compared to the other options.

4. An example of a non-renewable resource is E. coal. Non-renewable resources are natural resources that cannot be readily replaced by natural means at a quick enough pace to keep up with consumption. Coal is a fossil fuel formed over millions of years.

5. The part of a flower that attract pollinating agents is E. petal. Petals are often brightly colored and sometimes scented to attract insects and other animals for pollination.