The stage that scientists begin to ask questions and attempt to explain observations is A. forming hypotheses. This is because a hypothesis is basically a testable question about observations scientists make.
Answer:
I, II, III
Explanation:
A threshold stimulus is a stimulus that is capable to produce a response in excitable tissues such as neurons and muscle fibers. At threshold potential, the outward movement of K+ and inward movement of Na+ become equal to each other. When the potential exceeds the threshold potential, more and more Na+ enter the cell to depolarize it and to allow the opening of Na+ channels. Therefore, to fire an action potential, the threshold must be exceeded.
Conduction of action potential is all or none phenomenon which means that either it occurs or it does not occur. As an impulse is passed by each successive part of an exon, it enters the refractory period during which there is no conduction of nerve impulse. It ensures the one-way conduction of impulse from the cell body to the axon terminal only.
Answer:
Forest plantations are forest that stands established by planting and/or seeding in the process of afforestation or reforestation.
Explanation:
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Have a supercalifragilisticexpialidocious day!
Answer:
An animal with a backbone.
Explanation:
Answer:
1/4
Explanation:
Cystic fibrosis is a recessive disorder and therefore, is expressed only in homozygous recessive genotype. Let's assume that the allele "c" is responsible for the disease in the homozygous state. Since the couple already has a child with cystic fibrosis (cc), they both are heterozygous carriers for the disease.
The genotype of male and female each is "Cc". A cross between Cc x Cc gives progeny in the following phenotype ratio=1/4 diseased: 1/2 normal carriers: 1/4 normal. Therefore, the probability of getting a diseased child for them is 1/4.
