Reproduction In Animals

Gametes are involved in sexual mode of reproduction. The plants reproducing by sexual mode have both male and female reproductive parts and the animals have organs which produce gametes. In both cases, fusion of gametes is required for reproduction.

No. There are two modes of reproduction in organisms – asexual and sexual. The animals reproducing by sexual reproduction only give birth to young ones. Those reproducing by asexual mode adopt different methods but don’t give birth to young ones directly.

The young one of a cat is called a kitten and the young one of a frog is called a tadpole.

The two types of individuals based on sexuality are – male and female.

Sperms, which are male gametes are produced by testes.

The part in males through which both sperms and urine are passed out is called urethra.

Sperms are introduced into the vagina of a female, from where they quickly move to cervix.

Implantation is the stage in pregnancy where the rapidly growing and dividing embryo gets attached to the wall of uterus of the mother.

An embryo takes around 21days to completely develop into a chick. It is depicted by the hatching of egg that has been fertilized, and the emergence of chick from it.

Albumin in an egg functions to protect the embryo against external shock by forming a layer around it. It also provides nutrition to the growing embryo.

All mammals except platypus and echidnas are viviparous, that is they give birth to young ones.

There are four stages in the lifecycle of a silkworm.

1. Ova or egg

2. Larva, with five instars.

3. Pupae

4. Imago or adult.

Amoeba exhibits asexual mode of reproduction. It reproduces by binary fission, where a single organism, divides to form two new organisms or progeny.

There are five types of asexual reproduction. They are:

1. Budding

2. Binary fission

3. Fragmentation

4. Spore formation

5. Vegetative reproduction.

Animals which reproduce by budding are:

1. Hydra

2. Sea anemone

3. Corals

4. Sponges

5. Starfish

There are two modes of reproduction present in animals:

1. Asexual reproduction

2. Sexual reproduction

The female reproductive organs include a pair of ovaries, fallopian tubes, and a cervix.

Binary fission is an asexual mode of reproduction because it involves production of progeny from one single organism only, and no gametes are formed.

In the life inside uterus of the mother that is in intrauterine life, when the body parts of an embryo can be identified and differentiated, like the eyes, ears, hands, legs, etc. the embryo is called foetus. A mother gives delivery to a fully grown foetus.

Snail is hermaphrodite animal, as it has both male and female reproductive organs.

The animals that give birth to young ones directly, that is they do not pay eggs are called viviparous animals. The development of embryo, in this case, takes place inside the parental body, generally, of mothers.

Budding is a form of asexual reproduction, where new individuals develop from bulges or outgrowths on the parent body. These bulges are called buds, and hence the process is called budding. Being an asexual form of reproduction, it requires only one parent for the process.

Fertilisation has to take place for sexual reproduction to occur. It is one of the most vital steps in sexual reproduction. Fertilisation is the process of fusion of male and female gametes, to produce a new generation.

The advantages of reproduction are:

•It is a very rapid process, i.e. the progeny are produced very fast.

•A large number of progeny is produced in a single reproductive process.

•The new individuals are an exact copy of the parent, hence beneficial traits can be preserved.

•No mate is required, and they can reproduce in a wide range of environment.

After a fertilized egg is layer, the embryo takes around three weeks to develop into a chick. It requires the warmth provided by the hen sitting on it, to develop into a chick. As it develops completely, the egg hatches and the chick comes out.

The human male gamete, the sperm has to flow through the female reproductive tract to reach the fallopian tube, where it can fuse with the ovum. Thus, it requires an organ for rapid and efficient motility for transportation. The tail provides this function. The female gamete or the ovum has to travel very little distance, in which it is helped by the ovary and fallopian tube. Thus, it doesn’t require any tail.

The male gametes produced by testes are called sperms. These are small in size, single cells, with all the usual cell components. The sperms have three parts:

•Head

•Middle piece

•Tail.

AIDS is a sexually transmitted disease, which can be transmitted by:

•Unprotected sexual intercourse

•Through infected needle or syringe.

AIDS is a sexually transmitted disease, which can be transmitted by:

•Unprotected sexual intercourse

•Through infected needle or syringe.

Plastids, such as chloroplasts are four only in plant cells. Also, the plant cells have vacuoles and cell wall.

The life cycle of a frog is comprised of three stages, namely the egg, tadpole (larva) and the adult frog. In its life cycle, the frog shows drastic changes in the physical appearance of each stage. That is, the tadpole undergoes drastic changes to transform into an adult frog, in terms of body parts. This change is termed as metamorphosis.

•The first stage of life cycle of a frog is the egg. Eggs of a frog are present as a cluster and are slimy in nature. They hatch in around 3-25 days, depending on species and temperature of water. The hatched egg proceed to next stage, the tadpole.

•The second stage is the tadpole. These are long, slender organisms, which metamorphose into an adult frog, over weeks. It has an ill-defined head-body and tail, as body parts.

•The last stage is of the adult frog, which is the transformed tadpole. It has no tail, but limbs, and a properly differentiated body and head.

The two different ways in which zygote develops following an internal fertilisation is:

1. By oviparity; where the fertilized zygote after being coated with protective layers, is laid out as an egg, and the further development of the zygote takes place outside the body of the mother.

Example: Hen.

2. By viviparity; where the fertilized zygote gets implanted in the maternal body, and the development takes place inside the mother’s body. In this, the mother gives birth to young ones.

Cloning is defined as the process of generating copy of a cell, part of body, or a complete organism, which is genetically identical to the parent organism. It is a natural phenomenon seen in asexual reproduction. In artificial biological processes, the generation of an identical copy of desired cell or organism, which in nature show variations due to sexual reproduction, is called cloning. The process is generally used to produce cell or cell products with desirable traits. In molecular biology, the process of cloning is used to replicate DNA and RNA. The first successfully cloned animal was a sheep named Dolly.

The differences between menarche and menopause are as follows:

•Cell, the basic structural and functional unit of life, was discovered by Robert Hooke in 1665.

•He observed dead cells of a cork under magnifying device.

•The structure appeared to be like that of small rooms, arranged in a honeycomb pattern. Hence, the name cell.

•Further advancements in microscopy have led to description of cell in more details.