CELL DIVISION
MEIOSIS
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
a gamete containing an extra chromosome is formed
|
|
|
excessive sun exposure causes uncontrolled mitosis in skin cells
|
|
|
the DNA of a lung cell is damaged by exposure to cigarette smoke
|
|
|
a cell of a reproduction organ contains a damaged chromosome.
|
Detailed explanation-1: -Germ-line mutations occur in reproductive cells (sperm or eggs) and are passed to an organism’s offspring during sexual reproduction. Somatic mutations occur in non-reproductive cells; they are passed to daughter cells during mitosis but not to offspring during sexual reproduction.
Detailed explanation-2: -Germline mutations (that occur in eggs and sperm) can be passed on to offspring, while somatic mutations (that occur in body cells) are not passed on.
Detailed explanation-3: -An error in meiosis (called a non-disjunction event) causes the gamete to have an extra copy of a chromosome, and the resulting fertilized egg has a total of 47 chromosomes. It is also possible for a non-disjunction to happen after fertilization (about a 1-2% chance).
Detailed explanation-4: -A trisomy is a chromosomal condition characterised by an additional chromosome. A person with a trisomy has 47 chromosomes instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy.
Detailed explanation-5: -Germline mutations occur in gametes. These mutations are especially significant because they can be transmitted to offspring and every cell in the offspring will have the mutation.