A\(\rightarrow \) Anther. It produces pollen grains which are the male gametes.
B\(\rightarrow \) Style. It provides the path through which the pollen tube grows and reaches the ovary.
C\(\rightarrow \) Ovary. It contains ovules and each ovule has an egg cell / female gamete. It develops into fruit after fertilization.

Sexually transmitted diseases caused by
(i) Virus:
 (a) AIDS (Acquired Immune Deficiency Syndrome)
 (b) Genital warts
(ii) Bacteria:
 (a) Gonorrhoea
 (b) Syphilis
Transmission of such diseases can be prevented by the following ways:
 a) Screening tests for blood donors
 b) Mutually faithful monogamous relationships
 c) Educating people in high risk groups
d) Using condoms etc.

Prostate glands and seminal vesicles add fluid in the vas deferens. This makes transportation of sperms easier and also provides nutrition to the sperms.

(i) Barrier Method: In this method, physical devices such as condoms, diaphragm and cervical caps are used. These devices prevent the entry of sperm in the female
genital tract during copulation, thus acting' as a barrier between them. '
(ii) Hormonal Imbalance Method: In this method, specific drugs are used by females,which are of two types: oral pills and vaginal pills. Oral pills contain hormones
which stop the ovaries from releasing ovum into the fallopian tube. These pills are also called oral contraceptives (OCs) which act by changing the hormonal balance of the body so that eggs are not released and fertilisation cannot occur. The use of Intrauterine Contraceptive Devices (IUCDs) prevents implantation in the uterus. This device is copper- T placed safely inside the uterus by a doctor or nurse.
(iii) Surgical Method: In this method, a small portion of vas deferens in male and the fallopian tube in 'female is surgically removed or tied. It is called 'vasectomy' in males and 'tubectomy' in females. In this case, if the vas deferens in male is blocked, sperm transfer will be prevented and if the fallopian tube in the female is blocked, the egg will not be able to reach !he uterus, thus fertilisation will not take place

(ii) The site of fertilisation in human beings is in the fallopian tube of female reproductive system.

Reproduction is the process that helps in the growth of population of an organism.

Two functions of ovary:
To produce female gamete ovum
To secrete female hormones estrogen and progestrone.

Artificial method of vegetative propagation like cutting are used to grow rose plants.

DNA copying is not perfect accurate and the resultant errors are a source of variations in populations of organisms.

When a mature spirogyra filament attains considerable length, it breaks up into smaller fragments or pieces, and each fragment grows into a new filament or individual

The first and foremost reason for the appearance of variations among the progeny formed by sexual reproduction is, gene pool of the progeny is contributed by two different individuals. The second reason is that variations also happen during DNA replication before cell division.

(a)Menstruation and Periods.
(b)Puberty
(c)28 days

Secretions from seminal vesicles and prostate gland provide nutrition to the sperms. This makes transportation of sperms easier by providing them a fluid medium.

The importance of DNA copying during reproduction are:
(i) It is responsible for the transmission of parental characteristics to the offsprings.
(ii) During DNA copying in reproduction, the changes occur due to the inheritance of traits from both the parents. This lead to certain genetic variations, which are useful for the evolution of species over a period of time.

1. Testis: Testes are oval shaped primary reproductive organs in men. The function of testes is to produce sperms and male sex hormone testosterone. The scrotum provides optimal temperature for the formation of sperms.
2. Seminal vesicle: Seminal vesicles are a pair of thin walled muscular elongated which secrete fluid for nourishment of sperms.
3. Vas deferens: The sperms are carried by a long tube called vas deferens to organs called seminal vesicles where the sperms get nourishment and stored.
4. Ureter: It is the tube that carries urine from kidney to the urinary bladder. In humans, there are two ureters, one attached to each kidney.
5. Prostate glands: Prostate glands produce a fluid which is released in the urethra along with secretion of seminal vesicles for nourishment and transportation of sperms.

Characteristics of sexual reproduction are:
1. In sexual reproduction, two parents are involved (male and female).
2. The new organism produced is genetically different from both parents.
3. During gamete formation meiosis occurs. After fertilisation all divisions are mitotic.
4. Sexual reproduction helps in evolution.
5. Fertilisation of gametes leads to zygote formation. This zygote grows and develops to form a new organism.
6. Humans, fish, dogs, hens, cats, cows, horses, deer, rabbit, lions and tigers all reproduce by the method of sexual reproduction. Most of the flowering plants also reproduce by sexual reproduction.