31 questions in high school biology, high school biology. Question 29.

The answer is: a.

After iodine enters the rabbit's body, it enters the thyroid gland and synthesizes thyroid hormones one after another, so the iodine content in the thyroid gland has a tendency to decline from the highest point;

After the second injection, if thyroid hormone is injected, the thyroid gland will inhibit the secretion of thyroid hormone, and the curve will decrease more slowly (group C); In contrast, if thyroid-stimulating hormone is injected, the secretion of thyroid hormone will be promoted, and the curve will drop more rapidly (group B); The injected saline solution will be in the middle position (group A) because it is not disturbed, so the answer is A.

Option A Since non-radioactive thyroid hormone will inhibit the thyroid gland to synthesize thyroid hormone, non-radioactive thyroid-stimulating hormone will promote thyroid hormone synthesis by the thyroid gland, and saline will neither promote nor inhibit thyroid hormone synthesis Therefore, the corresponding curves are a, b, and c respectively

The use of iodine is to be used as a thyroid hormone, so iodine will be transported to the thyroid gland, so at the beginning of the radioactivity in the thyroid gland increases, if there is no radioactive thyroid-stimulating hormone, thyroid-stimulating hormone is used to promote the synthesis of thyroid hormone, and the synthetic thyroid hormone (which is radioactive iodine) should be released from the thyroid gland, so that the radioactivity in the thyroid gland drops the fastest, which should be curve b! If normal saline is injected, this is only a control, and the speed of thyroid hormone formation remains the same, so it should be the curve A in the middle, then if you inject thyroid hormone, the concentration of thyroid hormone increases, but it will inhibit the synthesis of thyroid hormone, so that the slowest drop in radioactivity in the thyroid gland should be curve C

The crux of the question is that it is not part of the modern view.

Therefore, b is incorrect, because what we have learned is that reproductive isolation is a sign of new speciation.

Mutations resulting from genetic mutations.

Option b Reproductive isolation is a necessary condition for the formation of new species.

1) Decomposer; Predation and competition.

2) carbon dioxide; The amount of energy flowing to the decomposer and the amount of energy cavity spike consumed by the respiration of the self-grinding body.

3) indirect; Resilience.

4) (This window is something that Wu Youbu can't draw).

C is the control, according to A and B when calculating O2 and CO2, the influence of C should be considered, through A knows, O2 = x + z, according to B knows, O2-Co2 = Y + Z, so CO2 = x-y, rq = (x-y) (x+z).

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Questions (1) and (2) of this question examine the principle of single variables in controlled trials: experiments should control for experimental variables, while other conditions should be consistent and appropriate. The experimental variable in question (1) is enzymes (with or without enzymes); The strain variable is the "effect" of the washing stool with enzyme laundry detergent, which is reflected by the time it takes to wash the stain.

The experimental variable in question (2) is temperature (one high and one low), and the variable is the same as in question (1). Grasp the single variable principle of the control barrage experiment, and the answer is about to come out

Question (3) Basis"Therefore"After that, it's easy to get the answer "add enzyme laundry detergent or protease"; According to the content behind the line, it is not difficult to know that "temperature" should be filled in here. Jujube answered.