Answer:
1. Signaling molecule
2. Signaling receptors
Explanation:
Hormones, growth factors, neurotransmitters, etc. serve the function of signaling molecules for cells. These molecules are released by one cell and bind to the receptors present on/in the target cells to elicit the desired response. Thereby, the signaling molecules serve in cell-cell communication.
For example, insulin hormone synthesized and released from beta cells of pancreas binds to its cell surface receptors present on the surfaces of liver cells and muscle cells to stimulate the uptake of the glucose from the blood.
Likewise, neurotransmitters released from the presynaptic neuron bind to receptors present on the membrane of postsynaptic neuron and serve to carry the nerve impulse to the postsynaptic neuron.
Answer:
Epidermal cells secrete the waxy hydrophobic substance cutin that polymerizes on the surface, forming a barrier to water evaporation. Epidermal cells are transparent because their plastids remain small and undifferentiated; hence light readily penetrates through to the photosynthetic tissues beneath the epidermis.
Explanation:
Answer:
both characteristic represent mitosis
Answer: b. The use of protein as an energy source is greater for endurance atheletes than those who body build or lift weights.
Explanation:
Proteins are the biomolecules. They are composed of polymers of amino acids. It is required by the body to repair tissues and build muscles, bones, and necessary component of skin, and cartilage.
The body of athletes require more protein than body builder or weight lifters. This is because during athletic practices like running, swimming and others the muscular mass should be strong enough to conduct long continous practice. The muscle mass is build up by proteins. The muscles may experience lack of oxygen during regular practice and may become weak. Thus require more protein so that the strength may remain maintained.
