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.

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

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.

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.

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.

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

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 primary sex organs produce gametes (sperms and ova).

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

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.

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.

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.

• Meaning - Reproduction is the production of young ones similar to their parents. It is an essential biological process for the continuation of the species and continuity of life.
• Two Types - All methods of reproduction fall into two categories: Asexual Reproduction and Sexual Reproduction.
• Asexual Reproduction - New individuals are produced without the fusion of gametes. Offspring are genetically identical to the parent (clones).
• Sexual Reproduction - Involves the fusion of male and female gametes, resulting in offspring with genetic variation from both parents.

• Meaning - Asexual reproduction involves only one parent, produces no fusion of gametes, and results in offspring that are genetically identical to the parent, called clones.
• Modes of Asexual Reproduction - Common methods include Binary Fission (Amoeba, Paramoecium), Fragmentation (Spirogyra), Budding (Yeast, Protosiphon), Spore Formation/Zoospores (Chlamydomonas), Conidia (Penicillium), and Gemmules (Marchantia).
• In Plants - Asexual reproduction in plants is called Vegetative Propagation. It can be Natural or Artificial (e.g., cutting, grafting, tissue culture).
• In Animals — Common in lower animals only. Does not involve meiosis or gamete formation. Lower animals reproduce asexually by budding and gemmule formation.
• Key Feature — Since only one parent is involved and no fusion occurs, all offspring are morphologically and genetically identical (clones) to the parent.

• Sexual reproduction involves the formation and fusion of male and female gametes (amphimixis) to form a zygote, with gamete formation by meiosis.
• It occurs in two phases: juvenile phase (no reproduction) and reproductive phase (sex organs active), regulated by hormones.
• It includes three main events: pre-fertilisation (gamete formation and transfer), fertilisation (fusion of gametes), and post-fertilisation (zygote and embryogenesis).
• Sexual reproduction produces genetic variation due to meiosis, recombination, and fertilisation, which is important for evolution.
• Primary sex organs (testes, ovaries) produce gametes, and organisms may be seasonal or continuous breeders depending on the reproduction pattern.

• Sexual reproduction involves the fusion of male and female gametes from two parents to form a diploid zygote.
• A flower is the reproductive structure in plants that produces gametes and enables fertilisation.
• A flower has four whorls: calyx, corolla, androecium (male), and gynoecium (female).
• It includes meiosis for gamete formation and fertilisation, producing genetically different offspring.
• Sexual reproduction occurs in three stages: pre-fertilisation, fertilisation, and post-fertilisation.

• The male reproductive system is located in the pelvic region and includes testes, accessory ducts, accessory glands, and external genitalia (penis and scrotum).
• Testes are the primary sex organs present in the scrotum; they contain seminiferous tubules where sperm are produced, while Leydig cells secrete testosterone, and Sertoli cells provide nourishment.
• Accessory ducts—rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct → urethra—help in storage, maturation, and transport of sperm.
• Accessory glands—seminal vesicles, prostate gland, and bulbourethral glands—add secretions like fructose, enzymes, and mucus, which nourish sperms and aid in their movement.
• The penis acts as the external genital organ, containing the urethra, and helps in the transfer of sperm during ejaculation.

• Includes — Ovaries, Fallopian tubes, Uterus, Cervix, Vagina, External genitalia, Bartholin's glands, Mammary glands — all in the pelvic region.
• Ovaries — outer cortex (follicles) + inner medulla; produce ova and ovarian hormones; release one ovum monthly after puberty.
• Fallopian tube — 3 parts: Infundibulum (fimbriae collect ovum) → Ampulla (site of fertilisation) → Isthmus (connects to uterus); cilia push egg towards uterus.
• Uterus — 3 layers: Perimetrium (outer), Myometrium (muscular), Endometrium (inner, menstrual changes); opens into vagina via cervix (birth canal).
• Zygote implants in the endometrium; the placenta connects the embryo to the mother for nutrient and waste exchange till birth.
• External genitalia — Mons pubis, Labia majora, Labia minora, Hymen, Clitoris. Bartholin's glands provide lubrication.
• Mammary glands — produce milk for newborn. Puberty begins at 10–14 years in females.

• Fertilisation in humans is the fusion of male and female gametes (sperm and ovum) and is an internal process occurring in the oviduct, leading to the formation of a diploid zygote.
• During copulation, millions of sperms are released into the vagina, but only one sperm reaches the ovum due to selection and protective barriers around the egg.
• Before fertilisation, sperm undergo capacitation and move towards the ovum; interaction between sperm and egg involves recognition molecules like fertilizin (ovum) and antifertilizin (sperm).
• The sperm’s acrosome releases enzymes that help digest the egg coverings (corona radiata and zona pellucida), allowing sperm entry through the membrane.
• After entry, the sperm nucleus and the ovum nucleus fuse (syngamy), forming a zygote (2n); this process restores the diploid chromosome number (46 in humans).
• Fertilisation triggers completion of meiosis II in the oocyte, formation of the second polar body, and formation of the female pronucleus and male pronucleus.
• In humans, sperm carry 22+X or 22+Y chromosomes, while ova carry 22+X only, determining the genetic sex of the offspring.