How Do Organisms Reproduce?

Budding is one of methods of asexual multiplication in which the cell division takes place at one specific site and turns out into an outgrowth. The little knob like projection turning out from the main body is known as a bud. The new life form grows there at the same site and get detached at when fully grown leaving behind the scar tissue. Since the proliferation is asexual, the recently made life form is a clone and is identical to the parent life form.

For example: budding in yeast

The spores are the minute, intense and resistant bodies which are round fit and can develop into another plant under reasonable conditions. The spore formation method of asexual reproduction is used by unicellular as well as multicellular organisms.

For example: Rhizopus, Mucor and some non-flowering plants.

Binary fission is a type of asexual reproduction which involves the splitting of parent organism into two new organisms. In this type of asexual reproduction the parent ceases to exist and two new forms come into existence.

For example: Amoeba, Paramecium etc.

Ovulation is the arrival of an egg from one of a lady's ovaries. After the egg is discharged, it goes down the fallopian tube, where fusion by a sperm cell may happen.

The role of placenta is to provide all the developing requirements to the developing foetus. These requirements are:

•Nutrition

•Respiration

•Excretion etc.

Testes are the primary reproductive structures or organs in males. Its function is

•To make sex cells i.e. male gametes called sperm.

•To make male sex hormone, testosterone.

Prostrate gland is a male reproductive organ which secretes prostrate fluid which is a component of semen. The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen. The secretions of seminal vesicle and prostrate gland provides nutrition to sperm and also make their further transport easy.

Ovaries are the primary reproductive organs in females. The function of ovaries is:

•To make mature female sex cells i.e. female gametes called ova

•To make female sex hormones, oestrogen and progesterone.

DNA is the carrier of genetic information. It is the blueprint of necessary information. For a parent to produce offspring of its own type, it is essential that the offspring carries same DNA as in parents. Thus, DNA copying or DNA replication is the only way through which a cell makes additional copies of same DNA which can be transmitted to its offspring. Thus DNA copying is an essential mechanism.

The organisms which have both male and female reproductive system within the same organism called bisexual organisms.

For example: earthworm, leech, starfish etc.

(i) Testis: Anthers

(ii) Ovary: ovary

(iii) Eggs: ovules

(iv) Sperms: pollens

Variation is defined as the slight difference in two organisms or species which distinguishes one from the other. Individual with variation has higher chances of survival since they are better adapted to the environment. Thus for survival of the fittest and to continue life on earth, variation is an important phenomenon.

Leishmania reproduces by the process of binary fission. It has a greater degree of organisation in its body, having a whip-like structure called flagellum at its one end. In Leishmania, the splitting of parent cell takes place in a definite plane {longitudinally} with respect to flagellum at its end.

(a) Mitosis:

It is important for:

•Increasing the number of cells in a particular tissue.

•Protection from harmful microorganism in case of a cut or wound.

•Replacing or repairing dead or inefficient cells in a tissue.

•To maintain the ratio of cytoplasm to nucleoplasm as well as surface area to volume.

(b) Meiosis:

•It is the most essential process in all sexually reproducing animals.

•Maintain chromosomal number in zygote (diploidity of zygote).

•Meiosis show crossing over, resulting in genetic recombination.

•Meiosis show a number of incidences of mutation (sudden changes in genetic material).

Significance of vegetative reproduction:

•Plants in which valuable characters of parents must be kept up, are proliferated vegetatively.

•The plants which don't deliver feasible seeds are proliferated by this method.

•Plants with decreased intensity of sexual multiplication, long lethargic time of seed or poor practicality are duplicated effectively through this method.

•Vegetative propagation likewise helps in expelling regular diseases from the parent plant.

In every ovulation cycle, an egg is discharged from the ovary which is exchanged to the fallopian tube. Also, the uterus sets itself up for a conceivable pregnancy. The lining of uterus thickens. At the point when no conception happens, the covering of the uterus is shed in pieces; alongside the unfertilized egg. These things are discharged out through the vagina through dying; called mensuration. The sole reason for the mensuration to occur is due the change in the levels of female hormones, oestrogen and progesterone.

Unicellular life forms dependably replicate by asexual reproduction; like binary fission, fragmentation, regeneration, sporulation etc. Multicellular forms, then again, utilize both asexual and sexual strategies for reproduction. While unicellular living beings normally take after the asexual strategies for propagation; the vast majority of the multicellular life forms take after sexual methods for generation.

Each specie needs to continually struggle for its survival. Characteristic predators and fancies of nature continue expelling a huge segment of the number of inhabitants in a specific animal types. In addition, the normal cycle of life and passing additionally expels a segment of the populace. Reproduction is an approach to recharge the lost segment of populace. In this manner, one might say that reproduction is connected to the soundness of populace of an animal varieties.

Vegetative propagation is a type of asexual reproduction. In this, new plants are produced by the parts of plants like stem, roots and leaves without the help of any reproductive organ. This technique is widely used in horticultural crop nurseries.

Advantages of vegetative propagation are:

•Plants in which valuable characters of parents must be kept up, are proliferated vegetatively.

•The plants which don't deliver feasible seeds are proliferated by this method.

•Plants with decreased intensity of sexual multiplication, long lethargic time of seed or poor practicality are duplicated effectively through this method.

•Vegetative propagation likewise helps in expelling regular diseases from the parent plant.

The transfer of pollen gains from the anther of a stamen to the stigma of a pistil or carpel is called pollination. The pollination is of two types:

•Self-pollination: when the pollen gains from the anther of a flower are transferred to the stigma of the same flower or another flower of same plant.

•Cross-pollination: when the pollen gains from the anther of a flower are transferred to the stigma of a flower of the other but similar plant.

Agents of pollination:

•Air

•Water

•Insects

•Bees and moths

•Butterflies and bats

Double fertilization is a type fertilization mechanism of flowering plants. This process involves the fusion of a female gametophyte (mega gametophyte also called the embryo sac) with two male gametes (sperm).

•The ovary of flower develops and becomes a fruit.

•The ovule of flower develops and becomes a seed.

The process of fertilization in plants

Difference between a gamete and zygote:

(a) A copy of something is known as a clone. During sexual multiplication, the characters in a posterity are attributes of their parents. Because of this, posterity framed after sexual multiplication show momentous similarity.

(b) The zygote located in the ovary in the flower after fertilization.

The swollen top of the stamen is called anther which makes the pollen grains and stores them.

The testes lie in the scrotum, because it helps in the formation of sperms because sperm formation requires lower temperature for sperm production.

Testes are the primary reproductive structures or organs in males. Its function is

•To make sex cells i.e. male gametes called sperm.

•To make male sex hormone, testosterone.

transport of sperms takes place in the following sequence: testis → vas deferens → urethra

Hepatitis is an inflammatory condition of liver caused by infection of hepatitis virus.

Sexual reproduction in flowering plants requires 2 types of gamete, fertilization is a compulsory event and it always results in formation of zygote.

plumule, cotyledon and radicle

Since the offspring formed from sexual reproduction has genetic material from two parents thus it exhibits more variations.

Reproduction is essential for all life forms to continue species generation after generation since for the existence of a race individuals are to be reproduced which is possible only through reproduction.

The cracking on voice in boys is due to the growth of voice box or larynx which can be seen as a protruding part of throat called Adam’s apple.

In every ovulation cycle, an egg is discharged from the ovary which is exchanged to the fallopian tube. Also, the uterus sets itself up for a conceivable pregnancy. The lining of uterus thickens. At the point when no conception happens, the covering of the uterus is shed in pieces; alongside the unfertilized egg. These things are discharged out through the vagina through dying; called mensuration.

Hyphae are the filamentous structures bearing sporangium at their tips which are the main mode of vegetative growth.

Vegetative propagation is a type of asexual reproduction. In this, new plants are produced by the parts of plants like stem, roots and leaves without the help of any reproductive organ.

Factors responsible for the rapid spread of bread mould on slices of bread are:

(i) large number of spores

(ii) availability of moisture and nutrients in bread

Length of pollen tube is the distance between pollen gain on upper surface of stigma and lower part of style.

Flowers are the sexual reproductive organs which after fertilization give rise to fruits.

unisexual flowers

(i) Possess either stamen or pistil

(ii) Exhibit cross-pollination

(iii) Possessing only stamens cannot produce fruits

Characters transmitted from parents to offspring are present in genes. They are the unit of hereditary.

The ability of a cell to divide into several cells during reproduction in Plasmodium is called multiple fission.

sequence of reproductive stages seen in flowering plants is gametes, zygote, embryo, and seedling

The number of chromosomes in parents and offspring’s of a particular species remains constant due to halving of chromosomes during gamete formation.

False

Menstruation lasts for about 3 to 7 days.

False

Ovary releases a egg every month.

False

The development of the child inside the mother’s body takes approximately nine months.

True

False

The female germs cells or eggs are made in the ovary.

False

The fertilization takes place in the ampullary-isthmus junction.

True

True

True

True