Answer:
A gene is a stretch of DNA or RNA that determines a certain trait. Genes mutate and can take two or more alternative forms; an allele is one of these forms of a gene. For example, the gene for eye color has several variations (alleles) such as an allele for blue eye color or an allele for brown eyes.
Explanation:
Exoskeleton
Exoskeleton is a evolutionary innovation. This is operated by muscles attached to it and acts as an armor. Other than support this is an adaptive mechanism to provide protection against predators. In vertebrates, it is considered as the dermal bone that developed via membranous ossification. Fishes retained their exoskeleton in the form of their scales. However, in some organisms terrestrial evolution allows the loss of exoskeleton and formed a more mobile endoskeleton,
The action potential spreads through an axon by depolarizing adjacent membrane to threshold.
- K+ departs the cell after Na+, which enters the cell first. Ions can move freely across the axon membrane because of the difference during the action potential.
- Because sodium contains a positive charge, the neuron becomes more positive and depolarized. Potassium channels take longer to open. As soon as the cell does open, K+ rushes out, reversing the depolarization known as repolarization.
- Sodium channels close during the peak of the action potential when potassium leaves the cell. When potassium ions are effluxed, the membrane potential is lowered or the cell becomes hyperpolarized.
- Outside of the cell, the concentration of Na+ is greater than inside the cell. while the concentration of K+ is is greater inside the cell than outside.
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Answer:
cell membrane, nucleus, and cytoplasm.
Explanation:
A cell consists of three parts: the cell membrane, the nucleus, and, between the two, the cytoplasm. Within the cytoplasm lie intricate arrangements of fine fibers and hundreds or even thousands of very tiny, but distinct, structures called organelles.
