A increases, curvature increases, B contracts, and curvature increases.
C magnification, curvature reduction D reduction, curvature reduction
2. When the electric eel catches its prey, it will discharge at a very high frequency. When similar electric eels hear the news, their "languages" for exchanging information are () a, action b, current c, sound d and smell.
3. Most fish can lay tens of thousands to millions of eggs in turn, but the mortality rate of fry is very high, so the number of adult fish is very small. The phenomenon that these fish lay eggs in large quantities is ()
A, adaptability B, relativity of adaptability
C, the result of long-term genetic variation D, the result restricted by abiotic factors
4. In order to test the carbon dioxide emitted by green plants during respiration, the necessary experimental condition is ().
A. use leafy plants. Immerse plants in water.
C. experiment in the dark. Use a seedling.
The success of organ transplantation is a great achievement of human medicine, because the organ transplanted into human body is not easy to survive. According to the concept of modern immunology, tissue cells implanted in organs are equivalent to ()
A. Tumor cells B. Damaged cells C. Antibody D. Antigen
6. Various antibiotics play an important role in treating diseases caused by bacterial infection. However, after using antibiotics for a period of time, the bactericidal effect will decrease. Explain it from Darwin's evolutionary point of view because ()
A. Selection of antibiotics by bacteria B. Selection of antibiotics by bacteria
C. Decline in product quality D. Decline in human physique
7, in the following, not as a variation example is ()
A. sheep have horns, but horses have no horns. B. Dairy cows produce high milk, while livestock produce low milk.
C. People's ears have earlobes, but there are no earlobes. D. Someone's vision changes from normal to myopia.
8. The former is a mollusk and the latter is an annelid ()
A scallop, hydra, squid, leech, earthworm, snail, mussel and centipede
After gas exchange in tissues, blood flowing through tissues becomes
A. arterial blood with more oxygen and less carbon dioxide
C venous blood with less oxygen and more carbon dioxide
10, scientists have done the following two experiments to prove a point: ① destroy the thyroid gland of tadpoles and find that tadpoles stop developing and cannot develop into adult frogs; (2) Put thyroid hormone into the water in the feeding trough, and tadpoles with damaged thyroid will develop into adult frogs. These two experiments can prove ()
A. Thyroid gland can secrete thyroid hormone B. Thyroid hormone can promote the development of young animals.
C. Growth hormone can promote the growth of tadpoles.
answer
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