Một loài vừa có khả năng sinh sản vô tính, vừa có khả năng sinh sản hữu tính. Hãy giải thích trong điều kiện như thế nào thì loài đó sinh sản vô tính, khi nào thì sinh sản hữu tính. Việc duy trì cả hai hình thức sinh sản có ý nghĩa gì?
Câu 1. Những sự kiện nào xảy ra ở các kì của nguyên phân đảm bảo cho sự phân chia đồng đều các nhiễm sắc thể về các tế bào con? Giải thích.
Câu 2. Những sự kiện nào xảy ra ở các kì của giảm phân đảm bảo cho cho số lượng nhiễm sắc thể giảm đi một nửa? Giải thích.
Câu 3. Phân biệt quá trình nguyên phân và giảm phân?
Writing sentence tranformation:
1.When did you start the project? -How long..............................................................
2.Their wedding will be held in a lovely church
-The church..............................................................
3.My father used to play football when he was young
My father doesn't..............................................................
4.Jane gave me a present on my last birthday.-I was..............................................................
5.How many people are there in our school?
We want to know..............................................................
6.This shirt is too dirtyfor me to wear.-This..............................................................
7.I don't find it difficult to get to get up early in the morning.
-I am.................................................
8.Would you please give me a hand ?
-Would.........................................................................
9.I wish I hadn't told him what we were planning to do that evening
I regret...............................................................................
10.This is the most delicious cake I have ever tasted.
-I............................................................................
11.At this moment,I only have time to think about my university thesis (preocupied)
At the moment,I......................................................................................
12.The value of US dollar has fallen considerably in the past week
-There.................................................................................
Write the conditinal sentences (Type 3)
1.We couln't help them that day because we had an extremely busy day
2.My brother didn't leave the ca keys,so I coudn't pick him up at the station
3.We spent too much money on our last holiday,so we had to borrow some from Mike after that.
4.We didn't go on holiday because we didn't have enough money
5.Peter got a terrible cough because he smoked a lot the previous night
6.Robert felt so sad and lonely because his girlfriend didn'y contact him.
7.Those people weren't prepared to face the floods;therefore,the consequence was disastrous
8.That village was heavily flooded last year because the trees in the forests wew cut dowb without control
9.We started our vacation too late,and we had to suffer bad weather.
10.She didn't take her friends' advice,she failed in her business.
Write mixed conditional sentences form these situations:
1.She is living in China because she got married to a Chinese
2.He has a test today,so he didn't go out last night
3.I am tired now because I went to bed late yesterday
4.She revised her lesson carefully last night.soshe gets a high score today.
5.He usually trains very hard.That's why he won the game last night easily
6.It rained so heavily yesterday,so the town gets flooded today.
7.I missed the end of the film so I don't know who the murderer was.
8.Ann carried heavy furniture when she helped her friend move.Her back hurts now.
9.I feel better now because you talked to me about myproblems last night
10.I am hungry now because I didn't eat lunch.
Thực hiện phép lai giữa các cây lưỡng bội (2n) cùng loài mang gen quy định tính trạng màu hoa thu được kết quả sau đây:
|
Phép lai |
Kiểu hình của P |
Đời con F1 |
|
1 |
Hoa đỏ X Hoa hồng |
60 cây hoa đỏ: 29 cây hoa hồng |
|
2 |
Hoa đỏ X Hoa trắng |
24 cây hoa đỏ: 25 cây hoa trắng |
|
3 |
Hoa đỏ X Hoa hồng |
27 cây hoa hồng : 55 cây hoa đỏ: 28 cây hoa trắng. |
Biết rằng, màu hoa do một gen nằm trên nhiễm sắc thể thường quy định. Biện luận và viết sơ đồ lai cho mỗi trường hợp.