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b The son's X chromosome comes from the father.

Color blindness is controlled by recessive genes, and if the mother is color blind, her genotype is: xbxb (let the gene that controls color blindness be b), and the father is not color blind, so her genotype is: xby.

The son is not colorblind and has a genotype: xxy. The father provides y, if x comes from the mother. The son is colorblind.

The genotype of the sire must be x(b)y

The mother must be x(b)x(b).

If the son does not suffer from color blindness, then there must be x(b), and the mother does not have x(b) so it must come from the father.

So choose B

The mother suffers from red-green blindness, so the mother has all the X chromosomes and the father is not sick, if it comes from the mother, both X's are sick, and the child is sick, so the son's extra X chromosome must come from. Father.

Summary. Dear, I'm glad to be able to answer for you, among the factors that cause gene frequency changes, mutations are the root cause of the creation of new alleles; Natural selection is a powerful factor that causes the change of gene frequency, and under specific selection conditions, the change of gene frequency is often directional, that is, the principle of "survival of the fittest, elimination of the unfit". Migration and genetic drift also affect changes in gene frequencies to some extent. In fact, changes in gene frequencies are often the result of a combination of two or more of these factors.

It can be seen that the frequency of genes has changed, and organisms may not have evolved. Hope it helps.

Dear, please introduce it in detail, so that we can answer it for you!

A change in gene frequency must mean biological evolution, and I've seen two different answers.

Dear, I'm glad to be able to answer for you, among the factors that cause gene frequency changes, mutations are the root cause of the creation of new alleles; Natural selection is a powerful factor that causes the change of gene Sun slip frequency, and under specific selection conditions, the change of gene frequency is often fixed, that is, following the principle of "survival of the fittest, elimination of the unfit". Migration and genetic drift also affect changes in gene frequencies to some extent. In fact, changes in gene frequencies are often the result of a combination of two or more of these factors. It can be seen that the frequency of genes has changed, and organisms may not have evolved.

Hope it helps.

But what I did said that a change in gene frequency must mean evolution.

Parenting, a common definition in textbooks, is "intergenerational changes in gene frequencies in a population". According to this definition, if you want to be more serious, the change in gene frequency is not the same as Huaifan, which must be evolutionary, because it is not necessarily full of lead and "generational" premise.

For example, Xiao Ming was hit by a car and died in a car, and at that moment the human gene frequency changed (although the change was minimal), but if you want to say that this letter pants led to the evolution of human beings, I am afraid it is unreasonable.

Evolution is generally discussed in terms of population, so changes in gene frequencies brought about by migration are indeed considered evolution.

According to modern evolutionary theory, it is clear that there is no evolution of what cannot be inherited (or that evolution only applies to traits that can be inherited). For example, young people suddenly have convulsions and go to kill Matt's hairstyle, although the trait changes obviously, it is not evolutionary.

So I'm going to keep the same point of view as in the answer to the question, that is, there must be biological evolution due to changes in gene frequency.

Kiss, yes.

(1) When the excitation is conducted, the charge distribution on both sides of the membrane at the excitation site is (negative on the outside and positive on the inside) (2) The synapse is composed of the presynaptic membrane, synaptic cleft, and postsynaptic membrane in the figure (fill in the serial number), and the characteristics of excitatory conduction here are (synaptic delay, one-way transmission).

3) When an excitation pass is completed, ACH is immediately decomposed. If a drug prevents the breakdown of ACH, it can cause (sustained muscle contractions).

4) A person's congenital ACH receptor structure abnormality will lead to (muscle contraction) The fundamental ** of such patients is (neurotransmitters cannot bind to receptors and cannot play a signaling role).

(1) (2) Read the textbook by yourself.

3) Continuous muscle contraction.

4) Muscles cannot contract Selective expression of genes.

You can all go and see for help.

The minus sign is preceded by the same and the result is 119764 32 = 2So the result is 1197-2=1195

PBO2 becomes PB2+ to get two electrons.

2Cr3+ becomes Cr2O72 to get 6 electrons.

So 1 molar Cr3+ can react with molar PBO2.

Then the amount of PBO2 required for the reaction with 1 mol Cr3+ is:

Moore B is right.

BCR2O7 2+ CR is +6 valence and changes to 3 valences.

PBO2 becomes PB2+, which is 2 valences.

The rise and fall of the chemical valence, PB changes from +4 to +2 and decreases by 2; CR changed from +3 to +6 and went up by 3; In order to maintain balance, 2 CRs correspond to 3 PBs, so B should be chosen

You're wrong......

Cr2O7 should be a divalent anion ......