Xét một cặp NST tương đồng chứa một cặp gen dị hợp (Aa ) , mỗi gen đều dài 4080 Awngstron . Gen A có 3120 liên kết hidro , gen lặn a có 3240 liên kết hidro .
a) Số lượng từng loại nu trong mỗi loại giao tử bình thường chứa gen nói trên bằng bao nhiêu ?
b) Nếu giảm phân I phân li binh thường , giảm phân II phân li không bình thường thì có những loại giao tử nào và số lượng từng loại nu trong mỗi loại giao tử bằng bao nhiêu ?
c) Kiểu gen BbDd cho các loại giao tử nào ? Nếu có sự rối loạn phân ly của cặp NST kép tương đồng trong lần giảm phân I , giảm phân II bình thường thì kiểu gen trên có thể cho ra các loại giao tử nào ?

phân số 9/120 được viết dưới dang số thập phân

 5,25 x 18 – 5,25 x 2 – 5,25 x 6 Tính bằng cách thuận tiện

3x^2-x/x^2-x - 2x+5/x+3 =1-4/x^2+2x-3

Cho e hỏi dùng Casio để bấm lượng giác thì khi nào dùng Shift, D và R ạ.

VD: hàm sin thì khi nào ta ấn sin khi nào ấn shift sin ạ

Câu 10: Một hệ ròng rọc được sử dụng để kéo vật B lên cao như trong hình vẽ. Biết vật A có trọng lượng 200N, mỗi ròng rọc có trọng lượng 5N. Bỏ qua ma sát và khối lượng của các dây treo.

a. Hỏi với hệ thống trên có thể nâng vật B có trọng lượng tối đa là bao nhiêu?

b. Tính hiệu suất của hệ ròng rọc.

thực đơn có vai trò j đối vs cơ thế? ở lừa tuổi này, em cần ăn uống ntn cho hợp lý                               

Ngày 30/4/1975, ai đã cắm lá cờ cách mạng trên nóc Dinh Độc lập

Số 420 có tất cả bao nhiêu ước số tự nhiên

Câu thơ sau của nhà thơ Tố Hữu ca ngợi những chiến sĩ trong chiến dịch nào?

Những đồng chí thân chôn làm giá súng

Đầu bịt lỗ châu mai

Băng mình qua núi thép gai

Aò ào vũ bão

đổi câu chủ động thành câu bị động

1.we have just seen an awful accident 

2. mrs Smith was making cakes at 7.00

3. he isn't going to by the house 

4. he hasn't seen you for years 

5.the examiner will read the passage 3 time

My father is painting our house at present.

My mother is cleaning the floor at the moment.

đổi câu chủ động thành câu bị động

1.my cousin will meet you at the station

2. she is running her own company

3.John hasn't finished his homwork 

4.they suggested banning advertisements on tv 

5. i will shut the door if you like

4. My mother is cleaning the floor at the moment. @ The floor 5. My father is painting our house at present. @ Our house 6. Her mother is preparing the dinner in the kitchen. @ The dinner 7. They are building some new houses down the street. @ Some new houses 8.Tom will visit his parents next month. @ His parents 9. The boss will meet him tomorrow in the restaurant. @ He 10. They are going to build a supermarket next year. @ A supermarket 11. The teacher is going to explain the lesson. @ The lesson 12. They moved the fridge into the living room. @ The fridge 13. She bought some cups of coffee for the visitors in the next room. @ Some cups of coffee 14. My sister was buying some food at 11 a.m yesterday. @ Some food 15. Her mother was preparing the dinner @ The dinner 16. My sisters were cleaning the floor at 7 o’clock last night. @ The floor 17. Mary was cutting the birthday cake @ The birthday cake 18. My friend has written ten emails @ Ten emails 19.The students have discussed the pollution problems @ The pollution problems 20. He has broken his nose in a football match. @ His nose 21. Somebody has taken some of my books . @ Some of my books 22. They have provided the victims with food and clothing. @ The victims 23. We should clean our teeth twice a day. @ Our teeth 24. We must solve this problem soon. @ This problem 25. Bill will invite Ann to the party. @ Ann 26. Nam can repair this sewing machine. @ This sewing machine

đổi câu chủ động thành câu bị động

1. someone had invented elctric lights before i was born

2. workers were digging a large hol in the ground

3. before they took exams they had revised their lessons

4. the car knocked a woman down in the street 

5. cows were eating grass on the meadow

Chiến thắng Điện Biên Phủ trên không là chiến thắng như thế nào?

Ở một loài thực vật thế hệ P có 80 cây có kiểu gen Aa và 20 cây có kiểu gen aa tự thụ phấn bắt buộc liên tục qua 3 thế hệ rồi tiếp tục giao phấn ngẫu nhiên . 

Hãy tính tỉ lệ kiểu gen khi các cây trên tự thụ phấn (F3) và giao phấn (F4)

Complete the e-mail. Use the correct form of the words in the box.
                     aim / save              complicated / work out               easy / work               great / have
                     someone / replace               place / stay               time / apply               important / get
                     sure / be               welcome / share               wonderful / hear
Hi Tasha,
Thanks for your letter. It was (0) …..wonderful to hear….. from you. Sorry I haven’t been in touch for a while - the new job is keeping me busy. I thought it would be (48) ……………..………… as a hotel receptionist but the job is more demanding than I expected. Some of the bills are quite (49) ………………… and of course it’s (50) ………………..………… for me ……………..………… them right. Having said that, it’s (51) ……………..………… a job. My (52) …………..………… is
…………..………… £500 by the end of the holidays - that will go a long way towards paying my
tuition fees next year. What are your plans? Why don’t you come here to work? It’s a good (53) ……………..……… for work in the restaurant. One of the waitresses left last week and they’re looking for (54) ……………..………… her. Don’t worry about finding a(n) (55) ………………..……… - you’re (56) ………………..……… my flat with me. They keep you busy here but there’s (57) …………………………..………… time for us to enjoy ourselves too. Think about it.
Erica.

Underline the correct answer.
12. A: I’d like to go / I like going on holiday to a different place every summer.
B: I’d like to go / I like going somewhere different this summer. Any ideas?
13. A: I regret to tell / telling you that your contract will not be renewed.
B: I regret to tell / telling you about it because it upset you.
14. A: He stopped to have / having coffee because it kept him awake at night.
B: He stopped to have / having a coffee and then he went back to work.
15. A: I know you’re tired but please try to concentrate / concentrating for a few more minutes.
B: I’m going to try to drink / drinking warm milk before I go to bed; it might help me sleep better.
16. A: Alice went on to act / acting until she was forced to retire because of her health.
B: Although Alice started out in television, she went on to act / acting on the stage.
17. A: He remembered to close / closing the windows so the rain didn’t get in.
B: He remembered to close / closing the windows so he was surprised to find them open when he got home.

Complete the extract from a story. Use the correct form of the verbs in brackets. Sometimes more than one form is possible.
She invited me (0) ….. to sit ….. (sit) down and then she excused herself from the room. I heard her (27) …………………………..………… (make) the tea in the kitchen and listened as she set out the cups and saucers. The room had begun (28) …………………………..………… (feel) a little odd and I regretted (29)……………………..………… (take) off my jacket. I noticed the fire (30) ………………………..……… (begin) to die down in the grate, watched second hand (31) …………………………..………… (move) slowly round the clock face and wondered how long it would be before she would allow me (32) …………………………..………… (leave). A few minutes later I heard the tea trolley (33) …………………………..………… (roll) on its wheels through the kitchen and then into the sitting room, where I was waiting. I started (34) …………………………..………… (drink) the tea she had poured for me and she let me (35) …………………………..………… (continue) in silence. I felt her (36)  …………………………..………… (watch) me and looked up quickly, hoping to catch her (37)
…………………………..………… (stare) at me, but she was looking instead at the cup of tea in my hand. Nervously, I sipped some more. It tasted slightly of bitter almonds but I carried on (38)
…………………………..………… (drink) it to be polite. At last I finished the unpleasant brew and set my cup down in the saucer. ‘Would you like me (39) …………………………..………… (pour) you another cup?’ she asked. ‘No thank you,’ I said, reaching unsteadily for my briefcase. ‘I must be going if I expect (40) …………………………..………… (be) home in time for dinner.’

bài 3 : give the correct form or tense of the verds in the brackets

1. You ever ( meet )                 a famous football player?

2. give old clothes to charity in stead of ( throw )          them away

3. where you ( go )                 on january 1st 2015?

4. If you ( not like )                this one,I will bring you another

Hãy giải thích vì sao NST là cơ sở vật chất chủ yếu của hiện tượng di truyền và biến dị ở cấp độ tế bào