The correct answer is D. Feed.

All living organisms require a source of energy to sustain their life processes, and they obtain this energy by consuming other organisms or organic matter. Photosynthesis is a process by which some organisms, such as plants, produce their own food using sunlight, but not all living organisms have the ability to do so. Respiration is a metabolic process that occurs in all living cells, but it is not exclusive to living organisms, as non-living cells can also undergo respiration. Movement is a characteristic of many living organisms, but not all, for example, plants may not move in the same way as animals. Therefore, feeding is the most fundamental characteristic of all living organisms.

Option B (Respire) is wrong : Respiration is indeed a characteristic of all living organisms, but it is not exclusive to them. Non-living cells can also undergo respiration, for example, yeast cells used in baking or wine-making. However, feeding is a characteristic that is exclusive to living organisms. Therefore, feeding is considered the most fundamental characteristic of all living organisms.

Explanation not provided, please join discuss, your contributions are welcomed

Explanation not provided, please join discuss, your contributions are welcomed

Explanation not provided, please join discuss, your contributions are welcomed

Explanation not provided, please join discuss, your contributions are welcomed

The correct answer is option A. 

Explanation: 
When the three glass tubes packed with clay, sand, and loamy soils are kept in a beaker of water for one week, the water will move through the soil and fill the empty spaces in the tubes. The level of water in the tubes will depend on the porosity of each soil type. 

Clay soil has smaller pores and is more tightly packed, which means it has less space for water to move through. This results in the lowest level of water in the tube with clay soil. 

Sand has larger pores and is less tightly packed, which means it has more space for water to move through. This results in a higher level of water in the tube with sandy soil. 

Loamy soil has a mixture of different particle sizes and is moderately packed, which means it has an intermediate level of porosity. Therefore, the water level in the tube with loamy soil will be somewhere between the levels in the tubes with clay and sand. 

Hence, the correct option is A - lowest in the tube with clay.

Explanation not provided, please join discuss, your contributions are welcomed

Explanation not provided, please join discuss, your contributions are welcomed

Explanation not provided, please join discuss, your contributions are welcomed

The correct answer is B. Fragmentation.

Explanation: 
Spirogyra is a filamentous green algae that reproduces vegetatively by fragmentation. In fragmentation, the filaments of Spirogyra break into smaller pieces, each of which grows into a new filament. This is a form of asexual reproduction, as no gametes or spores are involved. Binary fission and multiple fission are forms of cell division seen in unicellular organisms like bacteria and protozoans. Spore production is a mode of reproduction in fungi, algae, and some plants.