(i) The head comprises of two parts acrosome and nucleus.
(ii) Acrosome is a small cap like poin structure present at the tip of the nuel and is formed mainly from the golgi of the spermatid.
(iii) It contains hyaluronidase, a protein enzyme, popularly known as sperm lysin which helps to penetrate the ovum  fertilization.
(iv) The nucleus is flat and oval.

The negatively charged DNA is wrapped around the positively charged histone octamere to form a structure called nucleosome. A typical nucleosome contains 200 bp of DNA helix

Gypsy moth, fishes, reptiles and birds

When two different incompatible blood types are mixed, agglutination (clumping together) of erythrocytes (RBC) occurs. The basis of these chemical differences is due to the presence of antigens (surface antigens) on the membrane of RBC and epithelial cells.

Labia Majora, Labia Minora, Hymen and Clitoris

(i) Seminal plasma is alkaline in nature.
(ii) It contains fructose, ascorbic acid, prostaglandins and a coagulating enzyme called vesiculase.

Coitus interruptus is a oldest family planning method, where the male partner withdraws his penis before ejaculation, there by preventing the deposition of semen into vagina.

1. Genital herpes
2. Hepatitis -B
3. Genital warts
4. AIDS

All women are born with ovaries, but some do not have functional uterus. This condition is called Mayer- Rokitansky syndrome.

An ideal contraceptive should be user friendly easily available, with least side effects and should not interfere with sexual drive.

Government of India has taken various steps like PCPNDT Act (Preconception and Prenatal diagnostic technique act-1994) enacted to ban the identification of sex and to prevent the use of prenatal diagnostic techniques for selective abortion.

When normal vaginal delivery is not possible due to factors like position of the baby and nature of the placenta, the baby is delivered through a surgical incision in the woman's abdomen and uterus. It is also termed as abdominal delivery or Caesarean Section or 'C' Section.

(i) If the fertilised ovum is implanted outside the uterus it results in ectopic pregnancy.
(ii) The growth of the embryo may cause internal bleeding, infection and in some cases even death due to rupture of the fallopian tube.

The process of formation of placenta which is the intimate connection between foetus and uterine wall of the mother for exchange of nutrients is called Placentation.

Transfer of sperms by the male into the female genital tract is called Insemination.

(i) Sexual reproduction involves formation of gametes by meioses brings in exchange of chromosomal segments between paternal and maternal chromosomes.
(ii) Fertilization is a chance of probability because the ovum is can be fertilized by any of the sperms. Hence variations will occur and degree of variations cannot be predicted in sexual reproduction.

In nucleic acids (DNA and RNA), the nitrogenous base is chemically linked to one molecule of sugar forming a nucleotide.
When a phosphate group is attached to the nucleoside, it becomes a nucleotide. The nucleotides are polymerised to form a polynucleotide chain (DNA and RNA).

Purines	Pyrimidines
Purines have double carbon-nitrogen ring structures. Eg.Adenine and Guanine.	pyrimidines have single ring structure  Eg: Thymine, Cytosine and Uracil

A - Scolex
B - Neck
C - Immature proglottids
D - Mature proglottids
E - Gravid proglottids

Budding and Regeneration.

In artificial parthenogenesis, the unfertilized egg (ovum) is induced to develop into a complete individual by physical or chemical stimuli. E.g. Annelid and seaurchin eggs.

Juvenile phase I Vegetative phase, reproductive phasel maturity phase, Senescent phase.

conjugation is the temporary union of the two individuals of the same species. During their union both individuals, called the conjugants exchange certain amount of nuclear material (DNA) and then get separated. E.g. Paramecium

It is a type of fertilization. In exogamy, the male and female gametes are produced by different parents and they fuse to form a zygote. So it is biparental. E.g. Human - dioecious or unisexual animal.

A person with a recessive gene for haemophilia lacks a normal clotting substance (thromboplastin) in blood, hence minor injuries cause continuous bleeding, leading to death