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प्रश्न
From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions.
- Do larger organisms have more number of chromosomes/cells?
- Can organism with fewer chromosomes reproduce more easily than organisms with more number of chromosomes?
- More the number of chromosomes/cells greater is the DNA content. Justify.
उत्तर
Chromosome number of animals
| Animal | Chromosome Number | |
| 1. | Rat | 21 |
| 2. | Elephant | 56 |
| 3. | Giraffe | 30 |
| 4. | Cat | 38 |
| 5. | Horse | 64 |
Chromosome number of plants
| Plants | Chromosome Number | |
| 1. | Maize | 20 |
| 2. | Onion | 16 |
| 3. | Rice | 12 |
| 4. | Wheat | 42 |
| 5. | Mango | 40 |
- There is no correlation between the size of an organisms with the number of chromosomes present in the cells of its body. So, larger organisms do not have more number of chromosomes per cell.
- Process of reproduction follows a common pattern and is not dependent on the number of chromosomes in an organism. So, the organisms with fewer number of chromosomes need not reproduce more easily than the organisms with more number of chromosomes.
- Each chromosome is made up of DNA and protein. So, if a cell has more number of chromosomes, it will possess the greater DNA content.
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Our government has intentionally imposed strict conditions for M.T.P. in our country. Justify giving a reason.
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What substances are contained in oral pills, used as contraceptives? How do they work?
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The human males use a device X made of a very thin rubber sheet as a covering on the male organ to prevent pregnancy. This device traps the gametes Y in it. In order to prevent pregnancy, the human females use a device Z which is a circle of rubber with a metal spring around it. The device Z is put inside the vagina to cover the cervix. It stops Y from going into the uterus.
(a) What is device X?
(b) What are Y?
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(d) What is the general name of these methods of birth control (or preventing pregnancy)?
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John and Radha were classmates since childhood. When Radha became eleven years old, she developed a little swelling in her neck. She visited the doctor who started medication for her.
After a few years, John also developed a slight protrusion on his throat. He got worried and went to the doctor. But, the doctor assured him that it was a normal feature in boys while they are growing up. Can you think of any reasons for the difference in diagnoses?
Observe the chart and graph given in figure carefully and answer the following questions.
| Age in Years | % of full height | |
| Boys | Girls | |
| 8 | 72% | 77% |
| 9 | 75% | 81% |
| 10 | 78% | 84% |
| 11 | 81% | 88% |
| 12 | 84% | 91% |
| 13 | 88% | 95% |
| 14 | 92% | 98% |
| 15 | 95% | 99% |
| 16 | 98% | 99.5% |
| 17 | 99% | 100% |
| 18 | 100% | 100% |
- Which of the line represents the height of boys?
- Which line represents the height of girls?
- What is the difference between the pattern of increase in the height of boys and girls?
- Is this pattern true for each individual?
State one drawback of the following:
Copper - T
