Nhân tố sinh thái nào khi tác động lên quần thể sẽ bị chi phối bởi mật độ cá thể của quần thể?

A. Ánh sáng 

B. Nhiệt độ

C. Nước

D. Mối quan hệ kí sinh – vật chủ

Xét 4 tế bào sinh tinh của một cơ thể có kiểu gen AaBb giảm phân hình thành giao tử. Biết quá trình giảm phân diễn ra bình thường, tỷ lệ các loại giao tử có thể tạo ra là:

(1) 1:1       

(2) 3: 3:1:1.

(3) 2:2: 1:1.  

(4) 1: 1:1:1.    

(5)3:1.

Số phương án đúng

A. 4

B. 3

C. 2

D. 5

Bán kính nguyên tử của các nguyên tố: L 3 i ,   O 8 ,   F 9 ,   N 11 a  được sắp xếp theo thứ tự tăng dần từ trái sang phải là

A. F, Na, O, Li

B. F, Li, O, Na

C. F, O, Li, Na

D. Li, Na, O, F

Read the following passage and mark the letter A, B, C or D to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35.

GOING ON A DIET

Atypical person needs about 1,800 calories per day to stay running. They keep your organs operating (31) ______ and your brain running. They also keep your body warm. A person gains weight

because he or she consumes more calories per day than necessary. The only way to lose fat is to reduce the number of calories that you consume per day. This is the basic principle (32) ______ going on a diet.

Unfortunately, diets don’t work for most people. They do lose weight but then go off the diet and put it back. Building a sensible diet and exercise plan is the key to maintaining a consistent weight. You need to figure out how many calories you need in a day and how many you actually (33) ______. The next step is to add exercise so that you can raise the number of calories you can consume per day.

Burning 250 or 500 calories per day can make a big (34) ______. You can ride an exercise bike while you are watching television or you can take the stairs instead of the elevator. Find an exercise partner. Exercises can be a lot easier if there is someone to talk to. It’s a good idea to wear firm fitting clothes if you are (35) ______. Tight clothing acts as a reminder of what you are trying to accomplish.

Question 33

A. take off

B. take in

C. take up

D. take away

It is blowing so hard. We______ such a terrible storm.

A. never know               

B. had never known

C. have never known              

D. have never been knowing