问题 问答题

哺乳动物的生殖活动与光照周期有着密切联系。下图表示了光路信号通过视网膜→松果体途径对雄性动物生殖的调控。

(1)光暗信号调节的反射弧中,效应器是(),图中去甲肾上腺激素释放的过程中伴随着()信号到()信号的转变。

(2)褪黑素通过影响HPG轴发挥调节作用,该过程属于()调节,在HPG轴中,促性激素释放激素(GnRH)运输到(),促使其分泌黄体生成素(LH,一种促激素);LH随血液运输到睾丸,促使其增加雄激素的合成和分泌。

(3)若给止常雄性哺乳动物个体静脉注射一定剂量的LH,随后其血液中GnRH水平会(),原因是()。

答案

参考答案:

(1)松果体;电;化学

(2)体液(或激素);垂体

(3)降低;LH促进雄激素的分泌,雄激素抑制下丘脑分泌GnRH

选择题
单项选择题

Since 1975 advocates of humane treatment of animals have broadened their goals to oppose the use of animals for fur, leather, wool, and food. They have mounted protests against all forms of hunting and the trapping of animals in the wild. And they have joined environmentalists in urging protection of natural habitats from commercial or residential development. The occasion for these added emphases was the publication in 1975 of "Animal Liberation: A New Ethics for Our Treatment of Animals" by Peter Singer, formerly a professor of philosophy at Oxford University in England. This book gave a new impetus to the animal rights movement. The post-1975 animal rights activists are far more vocal than their predecessors, and the organizations to which they belong are generally more radical. Many new organizations are formed. The tactics of the activists are designed to catch the attention of the public.

Since the mid-1980s there have been frequent news reports about animal right organizations picketing stores that sell furs, harassing hunters in the wild, or breaking into laboratories to free animals. Some of the extreme organizations advocate the use of assault, armed terrorism, and death threats to make their point. Aside from making isolated attacks on people who wear fur coats or trying to prevent hunters from killing animals, most of the organizations have directed their tactics at institutions.

The results of the protests and other tactics have been mixed. Companies are reducing reliance on animal testing. Medical research has been somewhat curtailed by legal restrictions and the reluctance of younger workers to use animals in research. New tests have been developed to replace the use of animals. Some well-known designers have stopped using fur. While the public tends to agree that animals should be treated humanely, most people are unlikely to give up eating meat or wearing goods made from leather and wool.

Giving up genuine fur has become less of a problem, since fibers used to make fake fur such as the Japanese invention Kane car on can look almost identical to real fur. Some of the pest opposition to the animal rights movement has come from hunters and their organizations. But animal rights activists have succeeded in marshaling public opinion to press for state restrictions on hunting in several parts of the nation.

1975 was an important year in the history of animal treatment because()

A. many people began to call for humane treatment of animals that year

B. a new book was published that broadened the animal rights movement

C. the environmentalists began to show interest in animal protection

D. the trapping of animals began to go wild all through the world