问题 读图填空题

下列是生物生殖过程中染色体变化示意图,据图回答:

(1)请画出图中精子、卵细胞、受精卵细胞中染色体和基因。

(2)若图为人类生殖过程中染色体变化的示意图,图中所示的是一对性染色体,父方体细胞中性染色体组成为XY,则产生的精子有两种,分别为含_________和含_________性染色体,母方体细胞中的性染色体组成为_________,产生的卵细胞中只含_________性染色体。

(3)精子和卵细胞融合的过程叫_____________。

(4)从生殖细胞结合形成受精卵的角度看,决定生男生女的关键是由_________(生殖细胞)所决定,从理论上讲,男女比例大致是_____________。

答案

(1)“略”

(2)X   Y   XX   X 

(3)受精 

(4)精子  1:1

阅读理解

阅读理解。

     Australia is famous for its beautiful beaches. And Australian people love swimming and going to the beach.

But it wasn't always that way.

     Different Climate, Different Habits

     When Europeans first invaded Australia, the only people here who were good at swimming were the

Aboriginal people. The Europeans came from climates where it was too cold to swim. However the warm

climate of Australia soon changed their attitude to swimming. At first, only men swam. They swam without

any clothes on-there were no women to see them.

     Cover up!

     By the 1880 and 1890s visiting the beach was very fashionable. People wore everyday street clothes-much

more than people wear at the beach today.

     In those days people believed they should cover their most body so it would not be seen by the opposite

sex. Special bathing costumes were designed for women. This costumes used a lot of cloth and were very

heavy when wet, making it difficult to swim.

     Laws Made and Laws Changed

     The government decided to stop men swimming naked. It passed a law which forbade bathing between 6

am and 7 am. But in 1903, the laws changed; people could swim in the daytime, but they had to wear

neck-to-knee costumes.

     The Shrinking Costume

     As time passed, swimming costumes became smaller and more convenient.

     At first men and women were covered from neck to knee. Then arms became bare. Then more of the legs

were uncovered. Each new change was regarded by many as shocking and rude and people wrote letters to

the newspapers complaining about the new costume. Nowadays some people go to special"nude beaches" to

swim naked.

      However, most people cover their bodies more than they did ten years ago-not because they think bare

skin is shocking-but to protect their skin from the harmful rays of the sun.

1. Which of the following statements about the climate of Australia is TRUE?

A. It made European settlers think differently about swimming.

B. It changed European settlers' swimming costume.

C. It made European settlers feel much hotter.

D. It made European settlers have to swim naked.

2. What should swimmers do during the late 19th century?

A. They should hide when they meet a person of the opposite sex.

B. They should cover their body to avoid being seen by the opposite sex.

C. They should wear many heavy clothes on beaches.

D. They should wear special wet costumes designed for them.

3. What does the underlined sentence mean?

A. People were surprised by each new change and criticized it.

B. People were amazed by each new change and praise it.

C. Only newspapers were in favor of each new change.

D. Only newspapers thought poorly of each new change.

4. What can we conclude from the last paragraph?

A. People worry about getting skin cancer from too much sun.

B. People protected their swimming costumes from too much sun.

C. People are greatly shocked by the nude beaches.

D. People think it rude to swim with the smaller costumes.

单项选择题