Question

(a) List three distinguishing features between sexual and asexual types of reproduction. (5)(b) Explain why variations are observed in the offsprings of sexually reproducing organisms?

Answer 1

(a) Sexual Reproduction
1. It involves both the parent
2. It involves fusion of male and female gametes
3. It results in the introduction of variation in a population as newly formed organisms are not the exact copies of the parent


Asexual Reproduction
1. It involves only a single parent 
2. It does not involve fusion of gametes. The gamete of single parent undergoes division and gives rise to new a individual 
3. It does not bring variation in a population as the newly formed organisms are identical to the parents 


(b) In case of sexual reproduction, there is marked variation between the parent and offspring due to the following reasons:1. The male and female gametes are formed by meiotic division which allows crossing over and recombination. This generates variation in the genes of offspring.2. Two parents are involved who are different from each other. The fusion of their gametes would produce a distinct individual.

Answer 2

a)DIFFERENCES BETWEEN SEXUAL AND ASEXUAL REPRODUCTION;


ASEXUAL REPRODUCTION;
1) The production of new organisms from a single parent without the involvement of sex cells or gametes is called a sexual reproduction
2) Only one parent is needed
3) No fertilization takes place so no formation of the gametes.
4) Mitotic division is seen here.

SEXUAL REPRODUCTION;
1) The production of new organisms from two parents by making use of this sex cells is called as sexual reproduction
2) Two parents are needed
3) fertilization takes place so there is formation of the gametes
4) Meiotic division can be seen here .


b) VARIATIONS IN SEXUAL REPRODUCTION;

The replication of DNA in the cell is done by certain biochemical reactions which synthesis more of genetic material .
No biochemical reaction can reproduce 100% sem results so when the DNA already present in the nucleus of the parent cell is replicated by making more DNA at the time of a sexual reproduction then slightly variations come into copies formed.
Due to this the two DNA molecules formed by replication will be similar but may not be exactly identical to the original DNA The slightly variations in the replication of the DNA molecule will lead to slightly variations in the offspring produced by the a sexual reproduction .
The offsprings produced by a sexual reproduction are said to be genetically the same as the parent organism but still they have occasionally variations this means that the organisms do not always create exact copies of themselves in a sexual reproduction .




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