1. Reproduction in plants and animal

 

Reproduction is the biological process through which organisms produce offspring that are genetically identical to themselves.

 

 

Asexual reproduction:

In asexual reproduction, offspring are produced by a single parent (uniparental), and there is no fusion of gametes. Thus, the offspring produced are exact copies of the parent.

 

 

The process in which a male and a female gamete fuse to produce offspring of their own kind is known as sexual reproduction.

 

 

 

The transfer of pollen from anther to stigma is called pollination, which can be self-pollination (same plant) or cross-pollination (another plant of the same species).

 

Type of Pollination	Term and Example
Pollination by wind	Anemophily (e.g., maize, grasses)
Pollination by water	Hydrophily (e.g., Vallisneria, Hydrilla)
Pollination by insects	Entomophily (e.g., sunflower, hibiscus)
Pollination by birds	Ornithophily (e.g., hibiscus, Butea)
Pollination by bats	Chiropterophily (e.g., durian, kapok tree)

 

 

 

 

The reproductive system comprises of two different parts:

1. Primary reproductive sex organs -  It includes the gamete producing gonads, i.e., the testes (in a male) and the ovaries (in female).
2. Secondary or accessory reproductive sex organs.(Vas deferens and prostate gland etc. in males and Fallopian tubes and uterus etc. in females).

 

Male Reproductive System:

 

a. Structure of Testes: Male reproductive glands in the scrotum, each covered by tunica vaginalis, tunica albuginea, and tunica vasculosa, divided into \(~250\) lobules containing seminiferous tubules, Sertoli cells, and Leydig cells.
b. Spermatogenesis: Occurs in seminiferous tubules; Sertoli cells support sperm development and secrete inhibin to regulate FSH.
c. Hormone Secretion: Leydig cells between tubules secrete testosterone, which initiates and maintains spermatogenesis.

 

 

Female Reproductive System:

 

a. Structure and Function: The female reproductive system includes ovaries, fallopian tubes, uterus, vagina, and vulva, and its functions are to produce eggs, receive sperm, provide a site for fertilization and embryo development, and secrete hormones controlling ovulation and pregnancy.
b. Ovary & Follicle Development: Ovaries are almond-shaped organs with cortex (follicles) and medulla. Primordial follicles develop into primary \(\rightarrow\) secondary \(\rightarrow\) tertiary (Graafian) follicles, with the Graafian follicle releasing the ovum during ovulation. Females are born with \(1\)–\(2\) million eggs, but ovulate only \(300\)–\(400\) in a lifetime.
c. Accessory Organs & Glands: Fallopian tubes transport eggs and are sites of fertilization; uterus supports implantation and fetal development; vagina receives sperm and acts as birth canal; vulva is external genitalia; accessory glands include Bartholin’s glands and mammary glands for lubrication and lactation.

 

Gametogenesis is the process of the formation of gametes or sex cells, i.e., sperm in males (spermatogenesis) and ovum in females (oogenesis).

 

 

The menstrual cycle is a monthly (\(~28\) days) series of rhythmic reproductive changes in females, beginning at puberty (menarche, \(~11–13\ \)years) and ending at menopause (\(~48–50\) years).

 

 

 

Fertilization is the fusion of a haploid sperm and a haploid ovum to form a diploid zygote.

 

 

 

1. Embryogenesis & Gestation: Development from zygote to birth is called embryogenesis; it lasts ~280 days (gestation period).
2. Stages of Development: Includes cleavage (blastula formation) \(\rightarrow\) implantation (attachment to uterus) \(\rightarrow\) gastrulation (formation of ectoderm, mesoderm, endoderm) \(\rightarrow\) organogenesis (organ formation).
3. Placenta Function: Connects foetus to mother via umbilical cord; helps in nutrition, respiration, excretion, protection, and hormone secretion.
4. Pregnancy & Birth: Embryo develops in uterus; parturition is childbirth, triggered by hormones like oxytocin causing uterine contractions.
5. Lactation & Twins: Lactation is milk production (colostrum provides immunity); twins can be identical (one zygote) or fraternal (two zygotes).

 

 

• Contraception refers to methods used to prevent pregnancy.
• It includes barrier methods like condoms, hormonal pills, IUCDs, and surgical methods.
• It helps in family planning and controlling population growth.
• Certain methods like condoms also help prevent sexually transmitted infections.