Answer: Active transport is a process by which substances move against the concentration gradient. This process requires energy. Active transport is used in root hair cells of plants for the uptake of mineral ions that are present in lower concentration in the soil as compared to the root hair cells of the plants. This process uses energy derived from the mitochondria that are present in high amount in these root hair cells.
Nerve cells are also called neurons which are sdapted to perform their function of carrying messages in the form of electrical impulses from brain to the rest of body and vice versa. They consist of a long axon which helps in quick transmission of these electrical impulses over long distances througout the lenght of the body. The axon is insulated by a sheath of fatty tissue called the myelin sheath. This sheath provides insulation thereby increasing the speed of transmission. The cell body of the neurons have branches known as dendrites that help the neurons to receive multiple impulses from other neurons.
Diffusion in animals is used in the exchange of carbon dioxide and oxygen taking place in the alveoli of the lungs to replenish deoxygenated blood coming from the heart with oxygen.
