What is genetic variation?

Heredity is the similarity of offspring to their parents. For example, a sow gives birth to all piglets, not calves.

Variation is the difference between offspring and parents. For example, black pigs are not necessarily all black pigs, they may be flower pigs.

Heredity refers to traits that offspring have through genetic inheritance, and variation refers to traits that offspring have different traits from their parents due to genetic mutations, etc. For example, if both parents have blood type O, children can only have blood type O, if so, it is genetic, if not, it is mutated.

Heredity refers to traits that are the same as those of the parent and offspring.

Variation refers to traits that are not identical between the body and the offspring.

Hello, it's a pleasure to serve you and give you the following answer: High School Genetics and Variation in the Third Year of High School. Heredity and variation are important knowledge in biology, and they are the basis of biological evolution.

Heredity and variation refer to changes in the genetic makeup of an organism that can affect the traits of an organism. Reasons for the problem:1

Genetic variation may be due to environmental factors, such as radioactive materials, drugs, contaminants, etc., that affect the genome of an organism. 2.Genetic variation can also be due to genetic mutations within the organism, which can be due to empty residues due to genetic recombination, deletion, or insertion.

Workaround and practice steps:1First of all, it is necessary to understand the causes of genetic variation so that effective measures can be taken to prevent it from occurring.

2.Secondly, it is necessary to take effective measures to control environmental factors and reduce the impact on living organisms. 3.

Thirdly, effective measures should be taken to control gene mutations, such as using genetic engineering technology to change the structure of the genome to reduce the occurrence of gene mutations. 4.Finally, effective measures should be taken to control genetic variation, such as the use of genetic regulation technology to control gene expression, so as to reduce the occurrence of genetic variation.

Teaching & Personal Tips:1When teaching, students should understand the causes of genetic variation, so that they can take effective measures to prevent the occurrence of variation.

2.When teaching, students should understand the solutions and practical steps of genetic variation, so that effective measures can be taken to control the occurrence of genetic variation. 3.

Personal tip: Learn more about genetic variation so that you can better understand the causes and solutions of genetic variation, so as to better control the occurrence of genetic variation.

They differ in meaning due to different grammatical structures.

Heritable variation.

Variations can occur through genetics. "Genetic variation" is a phrase, causality.

Variation due to genetics.

Heritable variation, central word.

is "variation", "heritable" is a definite term, and the determinant variation is heritable or non-heritable.

Heritable variation refers to a factor such as genes; Heritable variation refers to the characteristics of the variation itself.

This question examines the concept of heritable variation and non-heritable variation, these two kinds of variation are divided according to the causes, the variation caused by the genetic material is the genetic variation, caused by the external environment, the genetic material has not changed for the non-heritable variation, but the environmental impact of the change of the genetic material will also produce genetic variation, such as artificially treating seeds with rays or drugs, which will cause changes in the genetic material of the seeds, and the offspring bred from these seeds will have genetic variations. However, in general, variations due to environmental conditions do not alter the genetic material and are not inherited. Once the above questions are clear, the answer to this question is clear.

Answer] d.

From the meaning of the title, the gray body is explicit. Let the control gene be a,a, then the genome of F2 becomes 1 3aa, 2 3aa

To find the ratio of gray fruit fly and black fruit fly, it is simple to find the ratio of black fruit fly AA.

AA can only be produced by 2 3 aa self-inbred, and its ratio is 2 3 * (2 3) * (1 4) = 1 9

Then Drosophila gray: Drosophila melanosophila = 8:1

Pure gray and pure black are hybridized to get gray, so the gray is black and hidden, and F1 is all BB. then bb x bb gets a quarter bb two-quarters bb a quarter bb. Only BB black. So gray is 3 to 1 compared to black

Ash is a dominant trait and is denoted as a. f1 is aa:aa:

aa=1：2：1。

The gray body is aa and aa, and the ratio is 1::a=2:1.

Self-inbreeding produces aa and aa and aa. In the offspring, the square of (a+a) = :aa:

aa=4：4：1。

Therefore the gray body is more black than the black body::1. Pick D.

The offspring of the BB*BB cross with the F1 gene are 1 2 BB and 1 2 BB, and the result is in three cases:

1 2bb*1 2bb, then the offspring is 1 4bb;

2*(1 2bb*1 2bb), then the offspring is 1 4bb, 1 4bb; 1 2bb*1 2bb, offspring 1 16bb, 1 8bb and 1 16bbSince BB is dead, so subtract its proportion to calculate that the proportion of BB alive is 6 15, then the proportion of B is 3 15, that is, 20%. Then the proportion of b is 80% hehe.

BB and BB plants were crossed to obtain F1, F1 was 1 2BB, 1 2BB, B gametes produced in F1 generation accounted for 3 4, B gametes accounted for 1 4, if the F2 obtained by random mating did not die, then BB accounted for 9 16, BB accounted for 6 16, BB accounted for 1 16, but due to BB death, so in the mature population, BB accounted for 9 15, BB accounted for 6 15, and the gene frequency of B gene was 9 15 + 6 15 * 1 2 = 12 15 = 4 5

f1bb1 2bb1 2, the two mate randomly, there are bb*bb, bb*bb, bb*bb. Let's do the math again, using the genotype method.

The F1 gene of BB*BB cross is 1 2 BB and 1 2 BB, and the result of F1 random assignment has three cases, 1 2BB*1 2BB, then the offspring is 1 4BB; 2*(1 2bb*1 2bb), then the offspring is 1 4bb, 1 4bb; 1 2bb*1 2bb, offspring 1 16bb, 1 8bb and 1 16bbSince BB is dead, so subtract its proportion to calculate that the proportion of BB alive is 6 15, then the proportion of B is 3 15, that is, 20%. Then the proportion of b is 80%.

In the F1 generation, there are only BB, BB

In the F2 generation, it is also BB, BB

In the F2 generation, it is a random mating, and only when BB*BB has 1 4 BBs killed. Thus, BB is left with 1 2 and BB 3 8.

Note that the frequency of b is being sought. b accounts for only 7 8 1 5

How do I think it's 75% that, there is no way that there will be a BB situation at all.

1.Rice is the least suitable (monoecious, small flowers. Yuan Longping was able to successfully engage in hybridization because he found male sterile rice. ）

A Drosophila: reproduces quickly, is abundant, and is a good hybrid material.

c Pea: a classic hybrid experimental material in textbooks, with large flowers, and self-pollination and closed-flower pollination.

d Corn: monoecious but heterogeneous, it is also an ideal hybrid material.

Trait segregation generally refers to the isolation of offspring with recessive traits from parents with dominant traits. The appearance of recessive traits must have recessive homozygous and will not separate traits. ）

3.Not entirely true: the number of male and female gametes in living organisms is not equal, and generally the number of male gametes is greater than that of female gametes, but the combination of female and male gametes is random.

1b Because the flowers of rice are too small to be manipulated2b In the hybrid offspring, only the appearance of recessive traits is homozygous.3 Fault In nature, the ratio of male and female gametes is more female than male.

2 to 1 Three pairs of genes are obviously not independent on the same chromosome, 2 B disease will not occur, then A and C are the same as the father left * mother left + father left * mother right 3 father right * mother right 1 4

4 The title is not stated.

5 No extensiveness.