What does it mean that there is both unity and diversity of life at the level of the cell?

All livings organisms are with unicellular origin. The cells have a common structure like cell membrane, DNA , RNA and necessary enzymes. The genetic code of protein synthesis is almost similar with few exceptions. This shows unity in design.

Further evolutionary changes took place due to environmental stress. The genome of each species is designed as per need and efficiency. This is diversity.

This is true with all five kingdoms of life that is monera, protista, fungi, plantae and animalia.

Explanation:

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.