How Do Organisms Reproduce (Sexual Reproduction) (Se...

Stamens and carpels are reproductive parts of a flower, which contain germ cells.

Birth control pills, use of mechanical barriers and blocking of fallopian tubes or vas deferens are contraceptive methods.

Bacterial infections such as gonorrhoea and syphilis, and viral infections such as warts and HIV AIDS are sexually transmitted diseases.

Two different types of gametes give rise to differences in the male and female reproductive organs and in some cases, differences in the bodies of the male and female organisms.

Transfer of pollen from anther to stigma is called pollination. Each pollen grain is a male haploid gametophyte, adapted to being transported to the female gametophyte, where it can effect fertilisation by producing the male gamete (or gametes, in the process of double fertilisation). 

Ovary in females and testis in males are the primary sex organs in humans.

The germ cells are called gametes. In humans, sperms are the male gametes and ovum is the female gamete.

The formation of germ cells or sperms takes place in the testes.

The sperm enters through the vaginal passage during sexual intercourse. It travels upwards and reaches the oviduct where it may encounter the egg.

Menstrual cycle starts at puberty in human female.

Gametes have half the number of chromosomes and half the amount of DNA as compared to the non-reproductive body cells.

Female germ cell possesses XX chromosomes, whereas male germ cell contains XY chromosomes.

In girls, breast size begins to increase with darkening of the skin of the nipples at the tips of the breasts. Also, girls begin to menstruate at around this time. Boys begin to have new thick hair growth on the face and their voices begin to crack.

The urethra forms a common passage for both the sperm and urine.

The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta.

Surgical methods can be used to create such blocks. While surgical methods are safe in the long run, surgery itself can cause infections and other problems if not performed properly. Surgery can also be used for removal of unwanted pregnancies.

After fertilisation, the zygote divides several times to form an embryo within the ovule. The ovule develops tough coating and is gradually converted into a seed. The ovary grows rapidly and ripens to form a fruit.

The fertilised egg, i.e. the zygote, gets implanted in the lining of the uterus and starts dividing.

The flower may be unisexual (papaya, watermelon) when it contains either stamens or carpels, or bisexual (hibiscus, mustard) when it contains both stamens and carpels.

The formation of germ cells or sperms takes place in the testes. These are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than the normal body temperature.