Answer:
- Mitosis occurs in all organism and is very important for them. In multicellular organisms,Mitosis allows the growth of cells, regeneration of organs and repairing of worn out cells. In asexually reproducing organisms mitosis is the process of reproduction. In unicellular organisms mitosis helps to produce identical copies.
- Some examples of Different types of asexual reproduction are as follows:
a) Fission- seen in <em>Amoeba</em>, <em>Paramecium </em>etc.
b) Budding- seen in <em>Hydra</em>, Yeast etc.
c) Fragmentation- seen in <em>Microstomum</em>
d) Zoospore - Motile asexual spores formed <em>Ectocarpus</em>, <em>Ulothrix </em>etc.
e) Vegetative propagation- Seen in plants that grow from parts other than seed.
3. Advantages of asexual reproduction:
i)No need of sexual partners.
ii) Genetic vigour of parent is preserved . Individuals are identical copies of parent.
iii) Rapid rate of reproduction.
4. Some Disadvantages of asexual reproduction:
i) No chance of obtaining new combination.
ii) Rapid reproduction leads to overcrowding and increased struggle for existence
5. The type of reproduction that involves the fusion of two gametes from different individuals is called sexual reproduction.
6. A gene has alternating forms, these forms are called alleles.
7. Sexual reproduction has greater variation because it involves recombination of traits from two parents.
8. All species do not have same chromosomes. Chromosome number is fixed for a particular species e.g. Humans have 46 chromosomes., Onion has 16 chromosome etc.
9. Human haploid cell contains 23 chromosomes.
10. Fusion of a haploid male and a female gamete to form a diploid cell called zygote is called fertilisation.
11. The first diploid cell that is formed after fertilization which can develop into a new organism is called zygote.
12. Diploid number is represented as 2n
Haploid number is represented as n.
