A few high school biology questions, requiring analytical answers

F1 is all AAB, AAB = A BB, so the number of such phenotypes is about the same.

Of course, it can also be calculated: thick purple is obvious, F1 is all AAB, thin shell violet = AAB = 1 4 * 3 4 = 3 16

Thick red = a bb = 3 16

It's AABCC. Because for each pair of genes, there are two dominant genes and recessive genes, so their gamete types are 2*2*2=8.

Because F2 has three types of genes for each pair of genes, pure dominant, pure recessive and heterozygous, there are 3*3*3=27 gene types of F2.

It was 9:3:3:1

F1 has only one phenotype.

There are 9 F2 genotypes.

The mRNA has U28% and A18%, so it is obtained by the principle of base complementary pairing, and there are A28% and T18% in one strand of DNA that is transcribed from it;

Again, the principle of base complementary pairing is applied, so there is T28% and A18% in the other DNA single strand. So in summary, there is t:(18%+28%) 2=23%, because it exists in pairs, so a must also have 23%, because c, g are also the same, a total of these 4 bases, so c or g are accounted for (1-2*23%) 2=27%, it can also be calculated like this:

RNA can act as an enzyme, but it is only a small fraction of the enzyme species and cannot catalyze all reactions.

b: tRNA can transport amino acids for protein synthesis.

C: The genetic material in some viruses (retroviruses) is RNA, which is transcribed into DNA after entering the host cell and then reproduced.

D: It is DNA, not RNA, that carries all the genetic information within the cells of an organism

7 C The skin thickness was AA, the color purple red was AABB, and the genotype of thin-shelled purple seed coat was AABBThe genotype of the thick-shelled red seed coat of peanut that can be stably inherited is AABBThe probability of occurrence is 1 16

The 8 A F1 genotype is AABCCSo the gametes are 2 = 4 and the genotype is 3 = 9.

9 b is 9:3:3:1

F1 has only one phenotype.

There are 9 F2 genotypes.

14 b The mRNA contains U28% and A18%, so using the principle of base complementary pairing, there are A28% and T18% in one strand of DNA from which it is transcribed; So a is, (18+28) 2=23

25 bc .Catalyzes a few biochemical reactions in cells that are catalyzed by RNA.

DNA carries all the genetic information within the cells of an organism.

In fact, the focus of these two answers lies in the question of whether the question is equal mass concentration or equal molar concentration.

If it is an equal mass concentration, as shown in the question, B should be chosen

If it is equal to the molar concentration, you should choose d,2,kathywu403 to report.

I think the focus of this question is whether glucose permeates the semi-permeable membrane, and the question says that the semipermeable membrane only allows water to permeate, and the same mass concentration means that the concentration of the two solutions is the same? Glucose must not pass through the semi-permeable membrane, and glucose enters the cell in the cell.

As shown in the figure, a water tank with a semi-permeable membrane (only allowing water molecules to pass through) is spaced at intervals, and equal concentrations of glucose solution and maltose solution are added to each side. Then the same mass of maltase is added on both sides of the semi-permeable membrane, and the change of liquid level on both sides of A and B before and after the addition of maltase is theoretically ( ).

A rises on the A side before the enzyme is added, and the B side rises after the enzyme is added and is equal to the height of the A side.

B rises on the A side before the enzyme is added, and the B side rises and is higher than the height of the A side after the enzyme is added.

C Before and after adding enzyme, the liquid surface on both sides of A and B remained unchanged.

D The liquid level on both sides of A and B remained unchanged before enzyme addition, and the height of B side rose and was higher than that of side A after enzyme addition.

When asked which one to choose B or D?

There is an answer to choose B, the reason is that the glucose molecule weight of glucose solution and maltose solution of equal mass concentration is small, the amount concentration of substances on side A is high, and there are more water molecules entering side A, and side A rises; After adding the same mass of maltase on both sides of the semi-permeable membrane, the 1 molecule of maltose on the B side is decomposed into two molecules of glucose, because the mass of 1 molecule of maltose is less than the mass of two molecules of glucose, the concentration of the substance on the B side is greater than the concentration of the substance on the A side, according to the principle of osmosis, the water molecules entering the B side increase, so the B side rises and is higher than the height of the A side after adding the enzyme.

Another answer is to choose D, the reason is that before adding enzymes, because the semi-permeable membrane can only permeate water molecules, but the concentration of glucose and maltose on both sides is equal, the water in and out is dynamically balanced, and the liquid level on both sides remains unchanged. After the addition of maltase, one molecule of maltose decomposes to produce two molecules of glucose, but the glucose side remains unchanged, and the concentration of the B side increases, so the water molecules are transported from side A to side B, causing the liquid level on side B to rise and be higher than the height of the liquid level on side A.

7/16 2/9

If you don't have a formula, you can only write it step by step.

f1 aa f2 1/4aa 1/2aa 1/4aa f3 3/8aa 1/4aa 3/8aa f4 7/16aa 1/8aa 7/16aa

Therefore, 7 16 are tall stems that can be stably inherited, and 2 9 are heterozygous in tall stems

Note: F3: 3 8AA=F2 1 4AA 1 4AA inbred 1 4AA+F2 1 2AA inbred 1 8AA=3 8AAA

And so on for the rest, including other offspring and AA.

Proportion of heterozygous = 1 (2 (n-1)).

The probability of a dominant (recessive) inheritance from inbred to the FN generation is 1 2-1 (2 n).

The proportion of heterozygous in the dominant trait from inbred to FN generation was 1 2 (n-1) (1 (2 (n-1))+2 n-1) 2 n).

1) The compound is made up of 3 amino acids, and the compound is called a tetrapeptide.

2) If a protein is synthesized (not through a peptide bond) with 4 of the above peptide chains, then:

16 amino acids, 4 amino groups, 8 carboxyl groups, 12 peptide bonds, and 3 R groups are required;

If the average relative molecular mass of each amino acid is 128, then the relative molecular mass of the compound formed by these 4 peptide chains is 1832. 128*4-3*18)*4 (the chemical reaction that occurs when the peptide chains are linked to each other is negligible).

3) The molecular structure of proteins is extremely diverse, because the types, numbers, and order of amino acids that make up various protein molecules are different, and the spatial structure of proteins composed of peptide chains is different

2.Experimental design: Verify that nickel is an essential inorganic salt for the growth of maize seedlings.

Materials and utensils: complete nutrient solution A, nickel-deficient complete nutrient solution B, suitable containers and fixing materials, corn seedlings with similar growth, inorganic salts containing nickel.

1): Method Steps:

Corn seedlings with similar growth were divided into two groups of the same number, numbered A and B

The maize seedlings of group A were cultured in complete nutrient solution B with nickel deficiency, and the maize seedlings of group B were cultured in complete nutrient solution A.

The two groups of corn seedlings were placed in the same suitable environment for several days to observe the growth of corn seedlings.

2) Experimental expectations: The growth of maize seedlings in group B was better than that in maize seedlings in group A

3) From the rigorous perspective of scientific research, in order to further confirm that the difference in the growth status of maize between groups A and B is caused by the difference of nickel**, what experimental steps should be added? The result?

Nickel-containing inorganic salts should be added to the nickel-deficient complete nutrient solution B of group A, and the growth of maize seedlings in group A was gradually the same as that of B, so nickel was the necessary inorganic salt for the growth of maize seedlings.

（1）.4 amino acids tripeptide.

2）.16 4 8 12 peptide bonds 3 R groups (128*4-18*3)*4=1832

3）.The types and numbers are different; The spatial conformation is not the same.

2.(1) The maize seedlings in group B were cultured and grown in complete nutrient solution.

2) The growth of group B was not as good as that of group A.

3) After that, inorganic salts containing nickel were added to group A and cultured again for observation. If growth is restored and is like group B, nickel is an essential inorganic salt for the growth of the plant.

Pick D. Analysis, the question asks that the amount of oxygen produced by photosynthesis is the total photosynthesis intensity, and the ordinate of the graph line represents the amount of oxygen released is the net photosynthesis intensity. At a light intensity of 2000lx, the net photosynthetic intensity was 17 ml h.

When the light intensity is 0, the plant cells only perform respiration, and the longitudinal intercept of the plot line represents the respiration intensity (6 ml h). According to the total photosynthesis intensity = net photosynthesis intensity + respiration intensity, the amount of oxygen produced by photosynthesis per hour of the plant at 2000lx light intensity is 17 + 6 = 23 (ml).

As can be seen from the figure, the respiration effect is 6

Oxygen release = photosynthesis production - respiration.

2000 is 17

Hence the choice D

d, because the total photosynthesis is calculated, it is necessary to add the respiration consumption, 17 + 6

First of all, I'll find fault with the topic, first.

1. Strictly speaking, the so-called oxygen release rate is at least 0, and there is a negative value in the figure, which is very puzzling; Clause.

2. When the science department publishes an article, the general ordinate coordinate representation is inverted, so the coordinate unit in this figure is difficult to read (ml h).

Of course, even if there is a problem with the question, it is not difficult to make an answer according to the logic of the question, when the light is 0, there is no doubt that oxygen is not produced, and the plant only consumes oxygen through respiration, that is, the oxygen consumption in the normal breathing state is 6ml h; In this way, at 2000 light intensity, oxygen is released as 17 ml h, but the breathing at this time also consumes 6 ml h, then photosynthesis produces a total of 17 + 6 = 23 (ml) of oxygen per hour.

1. Answer: B.

3. Analysis: Solution B is in a semi-permeable membrane pouch, and the number of water molecules is different due to the difference in the concentration of the solution on both sides of the semi-permeable membrane.

4. Analysis: Remember that when the water flows low, the volume of the solution in the pouch will become smaller.

5. Analysis: As obtained in the figure, the dotted line represents g, the number of water molecules in the bag is large, so there are many water molecules, and the liquid level in the glass tube changes greater.

6. Analysis: The ordinate of the coordinate diagram represents the degree of change of the liquid level, the highest point represents the starting point, the lowest point represents the end point, and the distance between the highest point and the lowest point represents the change in the glass tube.

Agree with the answer on the first floor, and explain it in detail.