Answer: Option B. -> menarche
:
B
The reproductive phase of a woman starts from her first period(menarche) at around 10-12 years of age. It continues until the age of 45 to 50, when women stop releasing eggs. This is called menopause. Hence, thereproductive phase of women lies between their menarche and menopause.

Answer: Option B. -> (22+1) pairs
:
B

• There are 22 pairs of autosomes and one pair of allosomes (also called sex chromosomes), thus a total of 23 pairs ofchromosomes.


• In human karyotype, the autosome pairs are labelled with numbers, while thesex chromosomes are labelled withletters. Females (44+XX) havetwo X chromosomes while males (44+XY) containone X and one Y chromosome.

Answer: Option A. -> True
:
A
The testis is the main functional part of the male reproductive system. Some specialised cells of the testis secrete the male hormone, testosterone during puberty. Testosterone is responsible for theformation of spermas well as secondary sexual characteristics in males.

Answer: Option B. -> Transfusion of infected blood
:
B
AIDS is caused by HIV virus. It can spread through various means like:
i. Sexual contact with an infected person.
ii. Transfusion of contaminated blood.
iii. From a pregnant mother to her child during birth or breastfeeding.
It does not spread by:
i. Touching, kissing and socialising with the infected person.
ii. Eating meals with an infected person.
iii. Mosquito bites.

Answer: Option D. -> Type of sperm
:
D
The sex of a foetus depends on thetype of sperm that meets the egg. A sperm carries either a Y chromosomeor an Xchromosome. Since women carry XX chromosomes, all egg cells (female gametes) formed will be X.If a sperm containing Y chromosomefertilises the egg, offspring will be male, whereas if an X chromosome containing sperm fertilises an egg, the embryo will be female.

Answer: Option A. -> endocrine glands
:
A
Glands without ducts are called "ductless" or "endocrine" glands. They release their secretions directly into the bloodstream. The pituitary is the master endocrine gland which regulates the secretions of other endocrine glands such as pancreas, thyroid glands, gonads, adrenal glands, etc. The secretions of endocrine glands are calledhormones.

Answer: Option A. -> True
:
A
The human body undergoes several changes during adolescence. These changes mark the onset of puberty. Puberty ends when an adolescent reaches reproductive maturity. The most conspicuous change during puberty is the sudden increase in height. At this time the bones of the arms and the legs elongate and make a person tall and thegrowth in the limbs usually happens first. The growth spurt characteristically occurs earlier in girls than in boys.

Answer: Option C. -> Breast development
:
C
One of the major changes in girls during puberty is the breast development. Also, in girls,the region below the waist becomes wider during puberty while in boys the chest becomes wider and shoulders become broad.

Answer: Option B. -> False
:
B
The sex chromosome pair in females consists of 2 X chromosomes. Hence, during egg formation, when the chromosome number is halved, all female gametes (egg) will receive the X chromosome. Males have one X and one Y in their sex chromosome pair. Therefore, the sex of the child dependson which sperm (X or Y) combines with the egg (X).

Answer: Option D. -> ovulation
:
D
Ovulation is the process in which mature ovaries release egg cell or the ovum. Usually, a single egg is produced during an ovulation cycle. The female hormone,oestrogen isreleased by the ovaries whichpromotes ovulation.