Revision: Life Processes in Living Organisms Part - 2 Science and Technology 2 SSC (English Medium) 10th Standard Maharashtra State Board

Reproduction is the process of formation of new individuals by sexual or asexual means, which can repeat the process in their own turn.

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Formation of new organism of same species by earlier existing organism is called as reproduction.

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Reproduction is a biological process that results in the formation of new individuals of the same kind, though usually with slight genetic, structural and physiological variations.

A mode of reproduction where a new organism is formed from a part of the parent body without involving gametes.

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The process of forming a new organism from an organism of the same species without the involvement of gametes is called asexual reproduction.

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When offspring is produced by a single parent by the formation of specialised asexual reproductive structures by the parent body, the reproduction is asexual.

A mode of reproduction involving the fusion of male and female gametes (sperm and egg) to form a zygote that develops into a new organism.

The period of growth and development before an organism becomes sexually mature is called the juvenile phase.

A flower that has only one reproductive whorl (either androecium or gynoecium) is called a unisexual flower.

• If it has only androecium: male flower
• If it has only gynoecium: female flower
  Example: Papaya

A specialised axis or branch over which flowers are produced or borne in definite manner is known as inflorescence.

A flower that has a stalk called pedicel for support is called a pedicellate flower.

A flower that has both androecium (male part) and gynoecium (female part) in the same flower is called a bisexual flower.
Example: Hibiscus

When pollination occurs between flowers on two different plants of the same species, it is called cross-pollination.

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Transfer of pollen grains from the anther of a flower from one plant to the stigma of the flower on another plant is called cross-pollination

Development of a new plant from a seed under favourable conditions is called seed germination.

Hernia is an abnormal condition that is caused when the intestine, due to the pressure in the abdomen, bulges into the scrotum through the inguinal canal.

Spermatogenesis is the process of formation and development of sperm cells (spermatozoa) in the testes from spermatogonial stem cells through mitosis and meiosis.

The secretion of glands with spermatozoa is a whitish viscous fluid known as seminal fluid or semen.

The process of expulsion of semen from the urethra is called ejaculation.

The opening of the vagina in young females is partially closed by a thin membrane called the hymen (or virgin knot).

Gametogenesis is the process by which male and female gametes are formed from germinal cells in the gonads through a series of developmental stages.

Spermiogenesis is the process of transforming spermatids into mature, flagellated spermatozoa (sperms).

The process of transformation of a circular spermatid to a spermatozoon is called spermiogenesis.

Gametogenesis is the process of formation of gametes i.e., sperms and ovary from the primary sex organs in all sexually reproducing organisms. Meiosis plays the most significant role in the process of gametogenesis.

Spermiation is the process of releasing mature spermatozoa. In this, spermatozoa are shed into the lumen of the seminiferous tubule for transport.

After spermiogenesis, sperm heads become embeded in sertoli cells from which they obtain their nutrition and finally get released into the lumen of seminiferous tubules. This process of release of mature sperms from sertoli cells is called spermiation.

The fusion of the male gamete (sperm) and female gamete (ovum) to form a zygote is called fertilisation.

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Formation of zygote by union of sperm and ovum is called as fertilization.

The formation of a zygote by the union of male and female gametes is known as fertilization.

A woman in whose uterus an embryo is implanted, and who carries the baby until birth on behalf of another woman, is called a surrogate mother.

If the embryo splits into two groups after 8 days of zygote formation, the resulting twins may be born with body parts joined together, and some organs may be common. Such twins are called conjoined twins.

When a single embryo divides into two groups of cells within 8 days after zygote formation, and both develop into separate embryos, they are called monozygotic twins.

When two embryos develop simultaneously in the same uterus and two offsprings are delivered at the same time, they are called twins.

• Sexual reproduction involves the formation and fusion of male and female gametes to form a zygote, which develops into a new organism.
• It is a slow, complex, and energy-expensive process, but it results in offspring that are genetically different from parents and from each other.
• Genetic variation arises due to meiosis, DNA recombination, and fertilisation, which is essential for evolution and natural selection.
• To maintain chromosome number, haploid gametes are formed by meiosis and fuse during fertilisation.
• Organisms must pass through a juvenile (vegetative) phase before entering the reproductive phase, which is regulated by hormones.
• Sexual maturity is marked by puberty in animals and flowering in plants; plants may be monocarpic or polycarpic.
• Based on breeding time, animals are classified as seasonal breeders or continuous breeders.

• Flower is the main reproductive organ in plants, made up of four whorls—calyx, corolla, androecium, and gynoecium.
• Essential whorls: Androecium (male) and Gynoecium (female);
  Accessory whorls: Calyx (sepals) and Corolla (petals).
• Bisexual flowers have both androecium and gynoecium (e.g., Hibiscus);
  Unisexual flowers have only one (e.g., Papaya).
• Gynoecium contains carpels with ovary, style, and stigma;
  Ovary has ovules, which form the embryo sac by meiosis.

• The male reproductive system is located in the pelvic region and consists of testes, ducts, glands, and external genitalia.
• A pair of testes present in the scrotum produce sperms in seminiferous tubules and secrete the hormone testosterone.
• Accessory ducts—rete testis, vasa efferentia, epididymis, vas deferens, and ejaculatory duct—transport and mature sperms.
• Accessory glands (seminal vesicles, prostate gland, and bulbourethral glands) add secretions that nourish sperms and aid their movement.
• The penis, containing the urethra, acts as the external genital organ for the delivery of sperms during ejaculation.

1. The female reproductive system includes a pair of ovaries, oviducts (fallopian tubes), a uterus, a vagina, and Bartholin’s glands.
2. All reproductive organs are located inside the abdominal cavity.
3. Ovaries release one ovum (egg) monthly after puberty, alternating between each ovary.
4. The egg enters the oviduct through its funnel-shaped end and is pushed towards the uterus by cilia.
5. Fertilisation usually occurs in the oviduct; the zygote implants in the uterus lining if formed.
6. The placenta connects the embryo to the mother for nutrient and waste exchange until birth.

1. Fertilisation is the union of sperm and ovum to form a zygote and is internal in humans.
2. During copulation, millions of sperms are ejaculated into the vagina, but only one sperm fertilises the ovum in the oviduct.
3. The acrosome of the sperm releases enzymes that help it penetrate the egg membrane; chemical changes then prevent entry of other sperms.
4. Fusion of sperm nucleus and egg nucleus restores the diploid chromosome number (46) in the zygote.
5. From puberty to menopause (45–50 years), only about 400 ova are released; ageing oocytes may lead to chromosomal abnormalities if fertilised.
6. Gametes are formed by meiosis: sperms are of two types (22+X or 22+Y), while ova are of one type (22+X); meiosis in ova completes during fertilisation.