Summary of two error-prone knowledge points in biology compulsory course
1, biological summary, help everyone, self-cross, cross, and hand it back?
Self-pollination: the same plant has cross-pollination (including self-pollination and cross-pollination of the same plant).
Hybridization: Sexual intercourse between different individuals.
Test crossing: F 1 or other organisms mating with invisible individuals can be used to determine the genotype or inheritance mode of the tested individuals.
Orthogonality and anti-intersection: the free definition of orthogonality and anti-intersection. If A is the female parent and B is the male parent, then the mating mode is called orthogonal, A is the male parent and B is the female parent. Orthogonality and backcross can be used to determine whether a certain inheritance is cytoplasmic or nuclear.
2. Why do you say that the methods to determine whether a trait is determined by nuclear genes or cytoplasmic genes are orthogonal and backcross?
Because the cytoplasmic genes are all from the female parent, and the genotypes of reciprocal crosses are different, the phenotypes of reciprocal crosses are also different. Therefore, the phenotype of reciprocal crossing is different from cytoplasmic inheritance.
When the nucleus is inherited, half the genes come from parents. For homozygous parents (homozygous by default in the textbook), the genotype of reciprocal cross is the same, so the phenotype of reciprocal cross is the same. Therefore, the same phenotype of reciprocal crossing is nuclear inheritance.
3. All genes of homozygote contain the same genetic information. What's wrong with this sentence?
Homozygous: One or more pairs of genes investigated are homozygous, regardless of other genes in the organism (either heterozygous or homozygous). Example: when testing the traits controlled by AABBDD gene, AABBDDEe is homozygous; When checking Ee, heterozygosity
4. Accurately describe alleles; Do homozygotes have alleles?
Genes that control relative traits at the same locus on homologous chromosomes are called alleles. alcoholic anonymous
Genes that control the same traits at the same locus on homologous chromosomes are called identical genes. alcoholic anonymous
5, 1. What experiment needs artificial castration? 2. Don't you need artificial castration if you cultivate alone?
1. Artificial emasculation can avoid unnecessary pollination in the experiment and eliminate the deviation of experimental results caused by pollen pollination of non-experimental parents.
2. Self-pollinated and closed-pollinated plants will be castrated if they don't need self-pollination in the experiment.
6. How many methods are there to test purebred?
There are two kinds-test crossing or self-crossing.
1. The progeny of test cross have character segregation, which indicates that the individuals to be tested are heterozygous. On the contrary, it is homozygous-this method is mostly used in animals.
2. Self-bred offspring have character segregation, which indicates that the individuals to be tested are heterozygous. On the contrary, it is homozygous-this method is mostly used for self-pollinating plants and the operation is very simple.
7. The essence of the law of free combination of genes: when F 1 produces gametes, alleles are separated and non-alleles are freely combined. What's wrong with this sentence?
There are two kinds of non-allelic genes, one is located on non-homologous chromosomes, following the law of free gene combination, and the other is located on the same pair of homologous chromosomes, following the law of gene chain exchange.
So this sentence should be like this: the essence of the law of free combination of genes: when F 1 produces gametes, alleles are separated and non-alleles on non-homologous chromosomes are free to combine.
8. In the Mendel experiment of two pairs of independent inheritance of relative traits, what is the proportion of individuals who can stably genetic recombination in F2? thank you
4/ 16 If aabb and aaBB cross can be stably inherited (aabb, AAbb, AABB, AABB).
The ratio of recombinant individuals (A_bb and aaB_) is 6/ 16.
4/ 16 If aaBB and aaBB cross can be stably inherited (aabb, AAbb, AAbb, AABB).
The ratio of recombinant individuals (A_B_ and aabb) is 10/ 16.
9. Does the genetic law of 9.ABO blood group not include the law of free gene combination? Why?
1, the genetic law of ABO blood group does not include the law of free combination of genes, because ABO blood group is controlled by multiple alleles IA, IB and I, and there is only separation.
2. If other blood types are included and there are dozens of pairs of genes related to blood types, then the law of free combination of genes can be included.
10. Does the amino acid synthesis process in protein need enzyme catalysis? If so, what kind of enzymes are needed?
The synthesis of protein requires enzymes. Mainly includes: helicase (transcription), RNA polymerase (transcription), amino acid condensation enzyme (translation) and so on.
1 1 and two pairs of genes with relative characters are freely combined. If the separation ratio of F2 is 9: 7, 9: 6: 1 and 15: 1, then the separation ratio of F 1 () is 65438 respectively.
If F2 is 9:7, it means that it is dominant only when it contains two AB's, so the ratio after test crossing is 1:3.
If F2 is 9:6: 1, only A or B containing 1 is neutral, so the ratio after test crossing is 1:2: 1.
If F2 is 15: 1, only A or B containing 1 is dominant, so the ratio after test crossing is 3: 1.
So the answers are 1:3, 1:2: 1 and 3: 1.
12. What factors do not follow the Mendel separation ratio?
1. Mendel's genetic law is only applicable to sexual reproduction, and it must not be followed if it is asexual reproduction.
2. For some special cases, such as an organism with Aa gene, the recessive homozygote (or dominant or heterozygote) in the offspring will die, leading to non-compliance.
3. Cytoplasmic inheritance is only related to the maternal side and does not have equal probability and does not follow.
4. There is always some discrepancy between ideal value and reality, which is the same reason.
13, heredity, what about this genetic problem? Especially genetic maps and inferences? Is there a word?
First, judge whether it is explicit or implicit: making something out of nothing is invisible; When a girl is sick, she is often hidden. It is often obvious to have a normal daughter.
If you are with X, your father will suffer from your daughter and your son will suffer from your mother. With x, the hidden mother will suffer the child, and the mother will suffer the father.
14. Why is the change of chromosome behavior during meiosis the cytological basis of the three major genetic laws? How to understand?
1) subtraction ⅰ: homologous chromosome separation is the cytological basis of gene separation;
2) Late stage of subtraction ⅰ: the free combination of non-homologous chromosomes is the cytological basis of the law of free combination of genes;
3) Subtraction Ⅰ tetrad stage: The possibility of cross-exchange of non-sister chromatids between homologous chromosomes is the cytological basis of gene linkage exchange.
15, who can provide some methods to distinguish mitosis from meiosis?
If the number of chromosomes is odd, subtract two; Second, if it is even; See if there are homologous chromosomes, and if not, subtract two.
Third, if there are homologous chromosomes, see if there are tetrad, synapse and other characteristic periods, and whether to reduce one.
If not, it's mitosis.
Homologous chromosomes are located in different genomes, and the chromosomes in a genome are all different.
Therefore, to see whether there are homologous chromosomes, we only need to see whether the chromosome lengths are the same or different. It doesn't matter if the chromosomes with the same shape are different in color when doing the problem, because the real chromosomes are color neutral.
Several concepts of biological meiosis.
I haven't understood several concepts of meiosis in my study recently (it is better to have pictures)
1. chromosome
2. Chromatid monomer
3. Homologous chromosome non-homologous chromosome
4. Sister chromatids
5. Tetrad
How to count it?
17, the process of genetic information from RNA to polypeptide chain needs RNA as an intermediary. Is this sentence correct?
There are three types of RNA: messenger RNA, transport RNA and ribosomal RNA. Among them, RNA carrying genetic information is messenger RNA, amino acids are transport RNA, and ribosomes are mainly composed of ribosomal RNA.
The site of genetic information from RNA to polypeptide chain is ribosome, and the tool of carrying amino acids is transporting RNA, which shows that the process of genetic information from RNA to polypeptide chain needs RNA as an intermediary.
Does the presence of 18, messenger RNA, transfer RNA and ribosomal RNA in the nucleus mean that all the above RNA are synthesized in the nucleus?
No. Chloroplasts and mitochondria also contain DNA that can be transcribed. At the same time, these two organelles also contain a small amount of ribosomes, so part of the protein synthesis process can be carried out in them, that is, not only transcription, but also translation takes place in mitochondria and chloroplasts.
19. The existence of nuclear membrane enables gene replication and expression to be completed in different regions. Why is it wrong?
Gene replication occurs in the nucleus, gene expression includes transcription and translation, and transcription also occurs in the nucleus. All wet.
20. In the process of exploring the genetic code, Crick found that three bases determine an amino acid. After that, nirenberg and Matthew chose.
Using protein's in vitro synthesis technology, they took four test tubes, added an amino acid (serine, tyrosine, phenylalanine and cysteine) to each test tube, and then added cell extracts from which DNA and messenger RNA were removed, as well as synthetic RNA polyuracil nucleotides. Results A peptide chain composed of phenylalanine appeared in the test tube with phenylalanine added.
This experiment shows that. Answer: UUU is the codon of phenylalanine-how did you come to this conclusion?
This experiment can prove that UU does not encode serine, UU does not encode tyrosine, UU does not encode cysteine, and UU can encode phenylalanine. So it can be interpreted that UUU is the codon of phenylalanine.
Summary of error-prone knowledge points in biology compulsory course II
2 1. Can you confirm that the name of an amino acid is a codon? So there are 64 codons or 6 1. Is the termination code also a codon?
There are 64 codons, of which 6 1 determines 20 amino acids and 3 stop codons do not determine amino acids. But stop codes are also codons.
22. Where did the 22.mRNA go after it was translated?
MRNA eventually degrades after translation. The mRNA of most prokaryotes is degraded by enzymes within a few minutes. In eukaryotic cells, the half-lives of different mRNA vary greatly, ranging from a few minutes to more than ten hours or even dozens of hours.
23. How many kinds of RNA are transported?
The number of codons that determine amino acids is the same, 6 1. The anticodon and codon on each transport RNA are corresponding. There are 64 codons. There are three stop codons. If the amino acid is not determined, there is no corresponding transport RNA.
24. What are fraternal twins? Identical twins?
Identical twins: twins whose fertilized egg develops into two fetuses are called identical twins. Identical twins have the same sex and similar appearance. If the two fetuses are not separated, conjoined malformation will be formed.
Fraternal twins: Two eggs are released from the ovary at the same time, and the two eggs are fertilized and developed into fetuses, which are called fraternal twins. Fetuses formed by fraternal twins can be the same or different in sex, and their appearance is similar to that of ordinary brothers and sisters.
25. If X-rays are used to induce gene mutation in citrus cells, when is the highest probability of gene mutation in citrus cells?
Interval. Because in the interval of cell division, chromosomes and DNA need to be copied, DNA replication needs to be unscrewed, and hydrogen bonds in double strands are opened, so the bases on DNA are the most unstable and prone to mutation.
26. How can you tell whether the problem occurs in the first division or the negative second division of meiosis? For example: XXY
XXY may be a combination of X and XY, indicating that homologous chromosomes have not separated, which is the first abnormal meiosis.
It may be that XX and Y are combined, or the homologous chromosomes are not separated. This is the first abnormal meiosis. It may be that the chromosomes formed by sister chromatids are not separated, which is the abnormality of the second meiosis.
27. Traits controlled by genes on the X chromosome are easily expressed in female individuals. What's the matter?
If it is a dominant gene on X chromosome, it is easy to express in female individuals. However, if it is an invisible gene on the X chromosome, it is easy to express in male individuals, because the Y chromosome often lacks fragments homologous to the X chromosome. For example, the incidence of color blindness in men in China is 7%, while that in women is only 0.5%.
28, how to judge whether it is heritable variation? Please take seedless watermelons and seedless tomatoes as examples, thank you!
Only the variation of genetic material changes can be inherited. The genetic material has not changed, but the variation caused by environmental changes has not been inherited.
Seedless watermelon-chromosome variation, heritability, seedless tomato-the genetic material has not changed, but the variation caused by growth is not inherited.
29. Seedless fruit can be obtained by treating unpollinated tomato buds with auxin solution with appropriate concentration. What is the chromosome number of fruit cells? As we all know, the number of chromosomes in tomato genome is n. The answer is 2N, but why?
The fruit obtained by treating unpollinated tomato buds with auxin solution with appropriate concentration is seedless, but tomatoes are actually seed coats and peels outside seeds, which are directly developed from the maternal somatic cells of tomato plants, so the seedless fruit obtained by treating unpollinated tomato buds with auxin solution with appropriate concentration is 2N.
30. Is the acquisition of seedless tomatoes related to hormones? The principle is simple. Tell me.
If you want to get seedless tomatoes, you must try to develop peels directly from the ovary wall without forming seeds. We also know that auxin in plant hormones can promote the development of fruits, and the formation of seeds requires fertilization. Seedless tomato cultivation is also carried out according to this principle. Before pollination, seedless tomatoes can be obtained by applying a certain concentration of auxin to the pistil stigma.
3 1. Is colchicine used to obtain seedless watermelon? Is colchicine a hormone?
The acquisition of seedless watermelon is a ligament union disorder. It is related to colchicine, but colchicine is not a hormone.
32. What is the difference between gene mutation and chromosome variation? Aren't they all changes in base pairs?
From the molecular level, gene mutation refers to the change of base pair composition or arrangement order of genes in structure. Chromosome variation is the change of chromosome structure or quantity; Gene mutation is invisible under the microscope, but chromosome variation is visible.
33. Will individuals with genotype aa become Aa or AA when dominant mutation occurs? Or is it possible for both?
Generally, only one mutation is considered: individuals with aa genotype will become Aa if there is a dominant mutation.
Individuals with genotype Aa become AA after recessive mutation, and their characters remain unchanged.
34. Somatic cell mutation and gene recombination? Also called genetic variation?
It is also called heritable variation, because heritable variation only means heritability, not heritability. If the mutation occurs in somatic cells, it can be inherited by asexual reproduction.
35. Does the exchange of non-homologous chromosome fragments belong to gene recombination?
The exchange of non-homologous chromosome fragments is chromosome variation, and the exchange of homologous chromosome fragments belongs to gene recombination.
Summary of two or three error-prone knowledge points in biology compulsory course
36. How to accurately judge the number of cell genomes according to images?
If there are several identical chromosomes, there are several chromosome groups.
37. Cells with genotype AAaaBBBB contain several genomes. Please be specific, and it is better to have a picture.
38. Genotypes are four genomes. Genome refers to a group of non-homologous chromosomes, that is, different in morphology and function. In case of this problem, just count the alleles of the same kind and repeat them several times. For example, AAaa has four or BBBB has four, which means four genomes.
39、? Haploid must be highly sterile? Why is it wrong?
For example, if the seedlings of diploid watermelon are treated with colchicine, autotetraploid can be obtained, and if the anthers of tetraploid are cultured in vitro, haploids with even numbers of the same genome can be obtained, which is fertile.
Octoploid triticale is allopolyploid, and its anthers can obtain even haploids with the same number of chromosomes through in vitro culture, but it is sterile. So haploids are not necessarily highly sterile.
40. What are the characteristics of haploid?
You can see some haplotypes, such as plant color, disease resistance and so on.
4 1. Does colchicine inhibit the synthesis of spindle filaments or disintegrate the formed spindle filaments? So will cells stop dividing? If chromosomes are not separated, how can chromosomes be doubled?
Colchicine can not only inhibit the synthesis of spindle filament (prophase), but also destroy the formed spindle filament. Colchicine prevents cell division. Centromere and division? Spindle silk? It doesn't matter, it is equivalent to the programmed expression of genes. When included? Chromatid? At a certain time, the centromere breaks and the number of chromosomes doubles.
42. All gene recombination occurs during meiosis, right? Can you explain this mistake?
False: Gene recombination can be divided into broad sense and narrow sense. Gene recombination in a narrow sense occurs in meiosis, while in a broad sense it includes meiosis, fertilization and genetic engineering.
43. Academician Yuan Longping's super hybrid rice and triticale are based on gene recombination and chromosome variation. Why are they suitable for planting in alpine regions? Please tell me the reason in detail.
China's hybrid rice was first cultivated successfully through three-line hybridization, and two types with different genetic traits were obtained through hybridization, so the principle is gene recombination, while octoploid triticale is a new variety artificially created and cultivated through interspecific (genus) hybridization and induced chromosome doubling, based on the principle of chromosome variation (chromosome doubling).
44. What are the problems that need attention in aquaculture?
1. The fundamental purpose of breeding is to cultivate new varieties with excellent characters (good stress resistance, good quality and high yield) in order to better serve mankind.
2, the selection of breeding methods should be based on specific breeding objectives, material characteristics, technical level and economic factors, comprehensive consideration, scientific decision:
① General crop breeding can choose hybrid breeding and haploid breeding;
② Mutation breeding (such as space breeding) or polyploid breeding can be selected to obtain special characters;
③ If we want to combine special traits, but the incompatibility of distant hybridization cannot be overcome, we can consider genetic engineering and cell engineering breeding, such as cultivating various engineering bacteria for biopharmaceuticals.
3. From the point of gene composition, the target genotype of breeding may be:
(1) homozygote, which is convenient for seed production, seed retention and popularization; ② Hybridization, making full use of heterosis.
45. Among a pair of relative traits, are there more dominant trait pairs than recessive trait pairs?
It must be wrong, because some species are often persecuted or attacked when certain traits are expressed by dominance in a specific environment, but on the contrary, this trait is controlled by recessive control and can adapt to the living environment.
46.aa genotype individuals account for 18%, and AA accounts for 6%. What is the frequency of a gene? How is this worked out?
The individuals with aa genotype accounted for 18%, Aa accounted for 6%, AA accounted for 76%, and the frequency of A gene was1aa+1/2aa =18%+12 * 76% = 56%.
47. According to the textbook, gene recombination can also change gene frequency. How does gene recombination change gene frequency?
Gene recombination makes offspring have multiple genotypes, at this time, the gene frequency is not changed.
But this result provides a source for the choice of environment. Through the choice of environment, even if a few individuals die, the gene frequency will definitely change. So, in fact, gene recombination and natural selection will affect gene frequency.
48, environmental changes will make biological adaptability variation?
No; Darwin thought that variation is not directional, but environmental directional selection variation. Although the variation of adapting to the environment will change with the change of the environment, this variation is primitive, not produced after the change of the environment.
49. Stone knife board is a precious vegetable, dioecious, which belongs to XY sex determination. Wild stone knives have narrow leaves and low yield. In a wild population, it is found that a few broadleaf stone knives (mutants) grow, both male and female, and the yield of male plants exceeds that of female plants.
If it has been proved that broad leaves are caused by gene mutation, there are two possibilities, one is dominant mutation and the other is recessive mutation. Please design a simple experimental scheme to judge (it is required to write the cross combination, the cross result and draw a conclusion)
Answer: 1 Several broad-leaved mutant plants with sexual hybridization were selected. If the wild type appears in the hybrid offspring; Otherwise,
Dominant mutation, if only mutation occurs in hybrid offspring, it is recessive mutation.
Can other cross combinations be used to judge? Can you help me analyze it?
You can also use (1) to select multiple wild-type plants for sexual hybridization. If only the wild type appears in the hybrid offspring, then the mutant is
Dominant mutation, if the hybrid offspring has a mutant, this mutant is a recessive mutation.
(2) Screening a batch of mutants and wild-type hybrids. If there are more mutants in the first generation than in the wild type, the mutants are dominant, and if there are fewer mutants in the first generation than in the wild type, the mutants are recessive.
50, the reasons for the formation of ecosystem diversity can be summarized as ()
A. Gene mutation and recombination B. Natural selection C. Coevolution D. Geographical isolation C. Why?