Revisionsheet 3 CH3 MODEL ANSWERS

Posts : 42 Join date : 2010-01-28

1. Complete the following sentences :

1. Heredity is the passing of traits from parents to offspring

2. the characteristics of the offspring are determined by the effect of inherited traits and the environment

3. organisms on Earth reproduce by two ways : sexual and asexual reproduction

4. asexual reproduction in organisms can be one of these forms:

budding ,forming spores or growing from body parts

5. yeast reproduce asexually by budding

6. each organism takes its traits from parents because of DNA in the nucleus

7. chromosomes are made up of proteins and DNA

8. DNA is short for deoxyribonucleic acid

9. Each kind of organism has it own number of chromosomes

10. DNA ladder consists of millions of rungs that are made up of four kinds of materials called bases

11. Each rung is made up of two kinds of bases called base pair

12. the rough fur in guinea pigs is a dominant trait

13. when a sperm cell combines with an egg cell, this process is called fertilization

14. In meiosis, each sex cell has half number of chromosomes of the parent cell

15. a pollen is produced in the flower's stamens, but an egg is produced in the flower's pistil

2. Rewrite the following sentences in the right way:

1) The bw in chicken is black color as it is dominant trait

The bw in chicken is erminette but it is dominant trait or recessive trait

2) The smooth fur of guinea pig is represented by Rr ,but the hybrid rough fur is represented by RR

The smooth fur of guinea pig is represented by rr ,but the hybrid rough fur is represented by Rr

3) The DNA of ameba reproduced asexually have different traits than the parent ,so they can survive well in the environment

The DNA of ameba reproduced asexually have the same traits of the parent ,so they can not survive well in the environment

3. Complete the following graphic organizer:

click on this link to see the graphic organizer:
http://www6.0zz0.com/2010/02/06/11/183447679.jpeg

4. give the scientific reason for each of the following:

mitosis and meiosis work together to form a new multicellular organism

because in meiosis egg cells and sperm cells are produced then join to form a fertilized cell that divides through mitosis to produce a multicellular organism
the offspring of some kind of organisms can not survive if the conditions of the environment changed

because its inherited traits in DNA from its parent are not unique to survive in the new changes in environment especially when it is reproduced asexually
the offspring of plants with red flowers and white flowers are not red or white

because in this case there is no dominant trait (red or white) so, the hybrid gene is not white or red , it is pink (rw)
survival of eggs fertilized outside is difficult.

Because eggs could dry out , freeze in very cold weather or being eaten by some animals

5. Imagine what could happen if :

the top of weeds, in a garden, are cut and the roots are left in the ground

weeds may grow back from the roots that were left in the soil
the conditions for a spore is not right.

It will not grow into anew organism
the sex cells have the same number of chromosomes like the body cells
If a sperm combines with an egg the number of chromosomes in the fertilized cell will be twice number of chromosomes it should be in the body cell (can't happen)

4. read carefully the following sentences, then, answer the questions about:

1) a sperm from a plant whose flowers are red fertilized an egg of another plant whose flowers are pink:

a) Draw the Punnett square of the possible offspring for the two parents
http://www6.0zz0.com/2010/02/06/10/772204587.jpeg

b) Is this reproduction asexual? Explain your answer

No because there are two parents producing sperms and eggs

c) What is the color of offspring's flowers that have more probability

The probabilities of red and pink flowers are equal (50 %)

5. complete the steps of mitosis shown in the following graphic organizer:

http://www6.0zz0.com/2010/02/06/11/600165639.jpeg

Subject: Re: Revisionsheet 3 CH3 MODEL ANSWERS Sat Feb 06, 2010 9:05 pm

thanks 4 the answers

Posts : 42 Join date : 2010-01-28

DEAR ,
NOT AT ALL,YOU WELCOME.ANY TIME,IF YOU CAN NOT GET ANY POINT PLEASE DO NOT BE HESITATED IN ASKING ME SO I DO MY BEST TO EXPLAIN IT FOR YOU.THANKS

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