High School Biology, 17 Questions, Why?

The answer is: a.

The codon is located on the RNA, and there is no base T on the RNA, so there are only two bases A and U on the biological RNA, and the two bases should be composed of at least four bases to form a codon in order to determine 14 kinds of amino acids;

If the codon consists of 1 base, there are only 2 codons, a and u;

If the codon consists of 2 bases, there are only 4 codons, AA, UU, AU, UA;

If the codon consists of 3 bases, there are only 8 codons, aaa, aau, aua, uaa, uaa, uuu, uau, uua;

If the codon consists of 4 bases, there are only 16 codons, which can determine 16 amino acids.

There are only 14 kinds of amino acids, and there are at least 14 kinds of codons that determine amino acids, and the codons are located on the RNA, and there are only two bases of RNA A and U in the question (the structure pattern of genetic material of alien organisms and terrestrial organisms is the same, so there is no T in the base composition of RNA, and there is no U in the base composition of DNA).

Let a codon of the organism be composed of at least n bases, and each base has two possibilities, and the codon composed of n bases has the possibility of 2 to the nth power, 2 to the n power must be greater than or equal to 14, and n must be at least 4

So choose A

If a codon has only 3 bases, there are only 6 kinds of amino acids according to the arrangement, which cannot meet the 14 kinds of amino acids in the question, so at least 4 kinds are required.

1) AA or AA, AA, AA

2）aa，aa，aa

Analysis: Dominant is sick! That is, both aa and aa are syndacty, i.e., a is syndacty.

Grandfather A Grandmother AA Maternal Grandfather A Maternal Grandmother AA Father AA Mother AA

Daughter 1 4aa 1 2 aa

When a daughter marries a syndactyly, the male genotype may be AA or AA, so all 3 genotypes may appear.

1.Females suffer: AA or AA Father:

AA Mother: AA Analysis: If the disease is a dominant disease, then the grandmother and maternal grandmother will inherit a gene A from the parents, then the parents should not have the disease, so the disease is a dominant disease, and the genes of the grandmother and maternal grandmother are AA.

And because both grandmothers and grandmothers will pass on a gene A to their parents, and both parents are sick, the parents' genes are AA.

2.aa or aa or aa

Analysis: The genes of male patients with syndactyly type I may be AA or AA. Females can also have AA or AA, so all genotypes can be.

Analysis: The genotype of the female may be AA or AA, and the genotype of the male is AA. There are two types of marriages: AA and AA, and AA and AA.

If it is AA and AA, the offspring must be diseased, with a 50% chance, and if it is AA and AA, the offspring have a half chance of being diseased, with 25% of the disease and 25% of the disease.

1.Female: AA or AA Father: AA Mother: AA

or AA or AA

1) Female patients: AA or AAFather's is AAMother's is AA

2) AA or AA or AA.

3) One-third. Explain the third question: the female patient's parents are both aa, so the probability ratio of the female patient's genotype is aa:

aa=1/3 ：2/3.The genotype of a normal male can only be AA.

So what a normal male gives must be the A gene, so 2 3 1 2 = 1 3

1) The possible genotype of the female patient: AA or AA analysis: because her grandfather and maternal grandfather are both patients, their genotype is A (whether the disease is controlled by the autosomal dominant gene), and her grandmother and maternal grandmother are normal, then their genotype is AA, and because both parents are patients, the genotype of both parents is AA, and it cannot be AA, so it can be seen that (2) the father is AA and the mother is AA.

3) The possible genotype of the offspring is AA, AA, AA(4)1 4 Analysis: The genotype of the female patient is (AA or AA) AA (normal male), and the genotype of the offspring may be 2AA, 4AA, 2AA, and the normal is AA, so the probability of normal offspring is 2 8, that is, 1 4.

Plants have the characteristics of photosynthetic lunch breaks.

Photosynthetic lunch break is a phenomenon in which plants decrease their light and action rate due to high temperature and low humidity.

When the temperature is higher than the optimal temperature for photosynthesis, the photosynthetic rate obviously decreases with the increase of temperature, which is due to the passivation, denaturation and even destruction of the relevant enzymes that catalyze the dark reaction caused by high temperature, and the change and damage of chloroplast structure caused by high temperature. The high temperature aggravates the respiration of plants, and the decrease in carbon dioxide solubility exceeds the decrease in oxygen solubility, which is conducive to photorespiration and not conducive to photosynthesis. At high temperatures, the transpiration rate of the leaves increases, the leaves lose water seriously, resulting in the closure of the stomata and the lack of carbon dioxide, and the combined effect of these factors will inevitably lead to a sharp decrease in the photosynthetic rate. When the temperature rises to the thermal limit, the net photosynthetic rate drops to zero, and if the temperature continues to rise, the leaves will wilt and even dry up and die due to severe water loss.

Therefore, the photosynthetic rate does not change linearly with the increase or decrease of light intensity, but can only be said to be roughly so, and there are many influencing factors.

Hope it helps! ~

I saw that the petrification that was written for a long time, as a person who came to tell you, the human education version does not have this content, the general air hole is closed, and the carbon dioxide is reduced. The aim is to reduce transpiration or water evaporation. If it is not a single course paper, answer it like this, and you should get a full score.

First, the net photosynthetic rate is greater than 0 during the daytime; The reason why it drops at noon is that when the light is too strong, the stomata will close, the carbon dioxide absorbed will decrease, and the net photosynthetic rate will decrease.

The answer is: a.

Since the probability of the disease in the population is 19%, so aa+aa=19%, aa=81%, this can be sold to launch a=,a=, and further calculate aa=,aa=2*, high.

So the probability that the wife's genotype is AA is: (aa) (aa+aa)=(, if the wife's genotype is AA, the husband's genotype is known to be AA, so the probability that they will have a normal child is:

18 19*1 2=9 19, then the probability of them giving birth to a sick child is: 1-9 19 = 10 19.

Figure A is the pyramid of quantities, and Figure B is the pyramid of energy.

The energy pyramid represents the energy in each trophic level in a food chain, because the energy is transferred in one direction and decreases step by step, so the higher the trophic level, the smaller the energy. The energy sedan chair hunger tower is always positive pyramid shaped.

The quantity pyramid represents the quantitative relationship between organisms at each trophic level, which is generally a positive pyramid shape, but there are exceptions such as a tree with a lot of insects and birds, then there will be an inverted pyramid ruler.

1) Quantity of energy.

2) a, reproduction mode and survival mode b, food chain layers.

I choose CAdjust the energy flow of ecosystems so that as much energy continues to flow as much as possible to the parts that are most beneficial to humans (i.e., rice and fish), while minimizing the consumption of weeds and carnivorous black fish.

Personally, I think D should be chosen

First of all, look at A, the energy is only from the side being eaten to the side eating, and communication refers to the relationship between each other, but this only has the energy from the deer to the wolf, and there is no wolf to the deer, so A is wrong. The competition of option b should be between animals at the same trophic level, but here wolves have a higher trophic level than deer, so there is no competition. Option C is right if it is co-evolution, natural selection does not talk about predators and ** eaters constantly choosing each other, so to achieve co-evolution, convergent evolution seems to say that similar or even the same structure is produced to adapt to the same conditions, and there should be differences in the living conditions of wolves and deer, so C is wrong, D is right.

D wolves eliminate weak deer, weak wolves do not get enough food to be eliminated, mutual selection, surviving deer and wolves can pass on excellent genes to offspring through breeding, after many years, deer and wolves have evolved, and now deer and wolves are running fast.