Science questions in details [4 marks ]

The differences between internal and external fertilization are:

Internal Fertilization	External Fertilization
In this type of fertilization, the fusion of male and female gametes takes place inside the body.	In this type of fertilization, the fusion of male and female gametes takes place outside the body.
In this type of fertilization, there are high chances of survival of offspring.	In this type of fertilization, there are low chances of survival of offspring.
In this type of fertilization, less numbers of eggs are produced.	In this type of fertilization, large numbers of eggs are produced.
Example: Cows, Hens, Human beings, etc.	Example: Fish, Frog, etc.

Asexual reproduction is a mode of reproduction in which only one parent is involved to reproduce offspring. In this type of reproduction, the offspring’s produced are exact copies of their parents. Asexual reproduction is generally observed in very small sized organisms. Examples of asexual reproduction are Binary fission, Budding, Fragmentation etc.
Budding: In this mode of asexual reproduction, a part of the organism starts bulging out and slowly it grows and develops into a separate individual.
Example: Hydra, yeast, etc.
Binary Fission: In this mode of asexual reproduction, a single cell divides into two halves.
Example: Bacteria, amoeba, etc.

Fertilization involves the fusion of the male and the female gamete. The male and the female gametes are released from the male and the female reproductive organs. Sperms or male gametes are released from the male reproductive organ i.e., the penis. These sperms then enter the female body through the vagina. Then, they travel through the fallopian tubes where they meet the eggs. Hence, the process of fertilization takes place in the fallopian tubes.

During fertilization, the haploid nucleus of the sperm and that of the ovum fuse with each other to form the zygote. This zygote divides to form an embryo which in turn develops into a foetus.

Although, mother gives birth to a baby but the baby is formed from the fertilisation of male and female gamete that comes from the father and mother, respectively. The nuclei of both the parent gametes fuse to form a zygote with new character combinations from both parents. Hence, the zygote formed from fertilisation have characters of both the parents. This zygote develops inside the female body (uterus) and finally takes birth as baby.

The term ‘metamorphosis’ is not used while describing human development because in human beings, body parts of an adult are present from the time of birth itself, i.e. while beginning of life as a baby and until you are an adult, the basic plan of body does not change. On the contrary, in metamorphosis, the parts of the adult are different from those at the time of birth.

Internal fertilization: Fertilization which takes place inside the female body is called internal fertilization. Internal fertilization occurs in many animals including humans, cows, dogs and hens. External fertilization: This type of fertilization in which the fusion of a male and a female gamete takes place outside the body of the female is called external fertilization. It is very common in aquatic animals such as fish, starfish, etc.

Amoeba is a Single celled organism. It reproduces by asexual reproduction. The process of reproduction begins by the division of its nucleus into two. This is followed by the division of its body into two. This type of reproduction is called binary fission.

Hydra reproduces by budding. In hydra, there may be one or more bulges. These bulges are the developing new individual and they are called buds. This bud then grows gradually to form a small hydra by developing a mouth and tentacles. The tiny new hydra detaches itself from the parent body and become new independent individual.

Amoeba reproduces by common asexual method called binary fission. In this method, Amoeba cell divides into two equal daughter cells. The nucleus of amoeba first divides into two parts. After that the cytoplasm of amoeba divides into two parts, one part around each nucleus. This leads to the formation of the two daughter Amoebae cell having a nucleus and its own cell organelles.