问题 实验题

猪的白毛和黑毛是一对相对性状,白毛由显性基因(A)控制,黑毛由隐性基因(a)控制。甲为供核母猪(基因组成为aa),乙为供卵细胞母猪(基因组成为AA),丙为代孕母猪(基因组成为 Aa)。根据下图回答问题。

(1)克隆猪的毛色性状为         ,其基因组成为           。

(2)若用一头白色公猪与供核母猪交配,产下的仔猪中有白猪和黑猪。那么这头公猪的基因组成为            ,其精子的基因组成为          。

答案

(1)黑毛   aa (2)Aa   A或a

题目分析:(1)因为生物的遗传物质在细胞核中,所以克隆猪与提供细胞核的甲羊一样,毛色为黑色,黑色是隐性性状,基因组成为aa。

(2)若用一头白色公猪与供核母猪交配,产下的仔猪中有白猪和黑猪,子代黑猪的基因组成为aa,一个a是供核母猪提供,还有一个a是白色公猪提供,所以白色公猪的基因组成是Aa,那么这头公猪产生的精子有两种,分别是含A或者a基因的。

点评:此题为基础题,难度一般,掌握控制生物性状的一对基因一个来自父方,一个来自母方,可以据此对父母的控制这一性状的基因组成作出判断。

阅读理解

阅读理解。

     Speeding off in a stolen car, the thief thinks he has got a great catch. But he is in for an unwelcome surprise.

The car is fitted with a remote immobilizer (远程控制器) and a radio signal from a control center miles away

will make sure that once the thief turns the engine off, he will not be able to start it again.

     The idea goes like this. A control box fitted to the car contains a mini-cell phone, a micro-processor and

memory and a GPS satellite positioning receiver. If the car is stolen, a coded (编码的) cell phone signal will tell

the control center to block the vehicle's engine management system and prevent the engine being restarted.

     In the UK, a set of technical fixes is already making life harder for car thieves. "The pattern of vehicle crime

has changed," says Martyr Randall, a security expert. He says it would only take him a few minutes to teach a

person how to steal a car, using a minimum of tools, but only if the car is more than 10 years old.

     Modern cars are far tougher to steal, as their engine management computer won't allow them to start unless

they receive a unique ID code beamed out by the ignition (点火) key. In the UK, technologies like this have

helped to achieve a 31% drop in vehicle crime since 1997.

     But determined thieves are still managing to find other ways to steal cars, often by getting hold of the owner's

keys. And key theft is responsible for 40% of the thefts of vehicles fitted with a tracking system.

     If the car travels 100 meters without the driver conforming (一致) the ID, the system will send a signal to

an operation center that it has been stolen. The 100-meter minimum avoids false alarm be- cause of some

possible errors of the GPS signal.

     Staff at the center will then contact the owner to confirm that the car really is missing and keep the police

informed of the vehicle's movements via the car's GPS unit.

1. What's the function of the remote immobilizer fitted to the car? [ ]

A. To help the police make a surprise attack on the car thief.

B. To order the car to lock automatically when stolen.

C. To prevent the car thief from restarting it once it stops.

D. To send a radio signal to inform the car owner of the theft.

2. The underlined sentence "The pattern of vehicle crime has changed" suggests that ____. [ ]

A. it takes less time for the car thief to do the stealing

B. many self-prepared too]s can be used for car theft

C. the theft becomes more difficult because of modern technology

D. the thief has lost interest in stealing cars over 10 years old

3. ____ is essential in making a modern car tougher to steal.[ ]

A. A micro-processor

B. A special ID code

C. A special cell phone

D. A GPS satellite positioning receiver

4. Why does the tracking system set a 100-meter minimum before sending an alarm to the operation center? [ ]

A. To leave time for the operation center to give an alarm.

B. To keep the police informed of the car's movement.

C. To give the driver time to contact the operation center.

D. To allow for possible mistakes in the GPS system.

5. What will the operation center do first after receiving an alarm?[ ]

A. Start the tracking system.

B. Stop the engine.

C. Contact the owner.

D. Locate the missing car.

单项选择题