What will be an ideal response?
What causes a change in the number of chromosomes?
Ans:
Aneuploidy involves changes in chromosome number by additions or deletions of less than a whole set. In this case organism gains or loses one or more chromosomes, but not a complete set. The cause of most aneuploid conditions is nondisjunction during meiosis and mitosis. Nondisjunction occurs spontaneously. In meiotic nondisjunction , the chromosomes may fail to disjoin at either the first or the second meiotic division. Nondisjunction at meiosis 1 is more frequent than that at meiosis II . Aneuploidy is nearly always deleterious because of genetic imbalance. Most common aneuploidy is trisomy. Down syndrome is an example of trisomy.
Monosomy is another kind of aneuploidy, which is caused by the loss of one chromosome in cell. Turner syndrome is an example of monosomy. women with Turner syndrome usually have only one copy of X chromosome in every cell.
Biology & Microbiology
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A chicken somatic cell carries 78
chromosomes. A chicken sperm cell will contain how many chromosomes?
a. 19 b. 39 c. 78 d. 156 e. 312
Biology & Microbiology
Sponge gemmules
a. are used in respiration. b. capture food. c. function in excretion. d. serve in digestion. e. are reproductive agents.
Biology & Microbiology
The term interface can be used to describe the surface across which molecules and ions are exchanged, often diffusing between external and internal environments or between organ systems
What part of the respiratory system forms the interface between the respiratory system and the circulatory system? A) Alveoli B) Trachea C) Pharynx D) Bronchioles
Biology & Microbiology
Mimosa plants spread their leaflets during the day and fold them at night. You decide to design an experiment to test whether Mimosa's leaf movements are controlled by a biological clock. Which experiment would be the best test of your hypothesis?
A) Growing the plant indoors and turning the lights on in the middle of the night. If a biological clock is controlling leaf movement, the leaves will open. B) Putting the plant under a bright light in the middle of the day. If the leaves close, a biological clock mechanism is ruled out. C) Subjecting the plant to a flash of red light in the middle of the night. If the leaves open at the usual time the next morning, a biological clock mechanism is ruled out. D) Putting the plant in a dark closet at nightfall. Check on the plant at noon the next day, while the plant is still in the closet. If the leaves are open, a biological clock is indicated.
Biology & Microbiology