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प्रश्न
Give a reason for the following:
Gametes must be produced by meiosis for sexual reproduction.
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उत्तर
Meiosis is a type of cell division that reduces the chromosome number by half, necessitating the production of gametes for sexual reproduction. Gametes are haploid cells, which means that they contain half the number of chromosomes present in diploid cells (such as somatic cells). During fertilisation, the resulting zygote has the full diploid chromosome number when two gametes (sperm and egg) with half the chromosome number each fuse. Variation in the population is a result of the genetic diversity that is necessary for progeny to inherit a distinctive combination of genetic material from both parents.
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संबंधित प्रश्न
What is the difference between chromatin fibre and chromosome?
Given below is a schematic diagram of a portion of DNA.
- How many strands are shown in the diagram?
- How many nucleotides have been shown in each strand?
- Name the parts numbered 1, 2, 3, 4 and 5 respectively.
- Name the DNA unit constituted by the parts 1, 2, 3 collectively.
“First meiotic division is the reduction division” what does the word ‘reduction’ refer to in this statement?
Expand the following biological abbreviations :
DNA
Mention the contribution of the scientist given below in the study of chromosome:
Sutton and Boveri
Choose the correct answer:
A 'V' shaped chromosomes has to _____________
Write the functional activity of the following structure:
Chromosome
Write the functional activity of the following structure:
Spindle fibers
Give Reason:
The Law of independent assortment holds good for the gene pairs that occur in different pairs of chromosomes.
Give Technical Term:
Transmission of characters through generations.
Multiple Choice Question
Chromosomal aberrations are caused by:
With the help of a neat labelled diagram, describe the structure of chromosome.
Define euploidy.
Match the following.
| 1. Autosomes | - | Trisomy 21 |
| 2. Diploid condition | - | 9 : 3 : 3 : 1 |
| 3. Allosome | - | 22 pair of chromosome |
| 4. Down’s syndrome | - | 2n |
| 5. Dihybrid ratio | - | 23rd pair of chromosome |
Differentiate between X-chromosome and Y-chromosome with reference to –
- length of non-homologous regions
- type as per the position of the centromere
The female gamete/egg cell of a human cell will have ______.
