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Chromosomes Video Lecture | Biology for Class 9

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FAQs on Chromosomes Video Lecture - Biology for Class 9

1. What are chromosomes and what are their functions?
Chromosomes are thread-like structures made up of DNA and proteins found in the nucleus of cells. They carry genetic information in the form of genes. The main function of chromosomes is to ensure the accurate transmission of genetic material from one generation to the next during cell division. They also play a role in determining an individual's traits and characteristics.
2. How many chromosomes are present in a human cell?
A human cell typically contains 46 chromosomes, arranged in 23 pairs. These pairs consist of 22 pairs of autosomes (non-sex chromosomes) and 1 pair of sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
3. What happens when there is an abnormality in the number or structure of chromosomes?
Abnormalities in the number or structure of chromosomes can lead to various genetic disorders or conditions. Some examples include Down syndrome, where there is an extra copy of chromosome 21, and Turner syndrome, where females are born with only one X chromosome. These abnormalities can result in physical and developmental differences in individuals.
4. How are chromosomes inherited?
Chromosomes are inherited in a process called meiosis. During meiosis, the parent cell's chromosomes duplicate and then divide twice, resulting in four daughter cells. Each daughter cell receives a unique combination of chromosomes, with half of the genetic material coming from the mother and the other half from the father. This process ensures genetic diversity and the passing on of traits from one generation to the next.
5. Can changes occur in chromosomes over time?
Yes, changes can occur in chromosomes over time. These changes, known as mutations, can happen spontaneously or as a result of external factors such as radiation or exposure to certain chemicals. Mutations can alter the structure or number of chromosomes, leading to genetic disorders or variations in traits. However, not all chromosome changes are harmful and some may even contribute to genetic diversity and evolution.
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