Science questions in short. [2 marks ]

The transformation of the larva into an adult through drastic changes is called metamorphosis. It is a biological process which involves sudden and abrupt changes in the body structure of the animal by cell growth and differentiation. It is generally observed in amphibians and insects. Example: Frogs, butterflies, etc.

The transformation of the larva into an adult through drastic changes is called metamorphosis. Metamorphosis occurs in frog and silk moth.

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.

Difference between viviparous animals and oviparous animals:

Viviparous animals	Oviparous animals
The animals which give birth to young ones are called viviparous animals	The animals which lay eggs are called oviparous animals.
Examples: human, cow.	Example: Hens and frog.

The animals which give birth to young ones are called viviparous animals. Human beings and cow are examples of viviparous animals.

Reproduction is important for organisms because it ensures the continuity of life on earth. It is the means of multiplication and perpetuation of a species. It also creates variations among the population.

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 .figure represents binary fission with a dividing nucleus parent in Amoeba. The singlecelled parent Amoeba divides to form two daughter cells that develop into two independent Amoebae.

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.

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.

Fishes and frogs fertilise externally producing enormous number of gametes because some eggs may be lost due to environmental agents like flowing water, wind, etc. and this increases the chances of fertilisation.

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.

Oviparous animals: Frog, sparrow, lizard, hen, fish, butterfly.
Viviparous animals: Human being, dog, cat.

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

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.

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.

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

Viviparous animals: Cow, deer, cat, tiger, dog.
Oviparous animals: Ostrich, frog, lizard, snake, hen.

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

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

Sexual method: Cats, humans, birds.
Asexual method: Amoeba and Hydra.

Frog and silk moth undergo metamorphosis whereas cow and hen do not undergo metamorphosis.

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

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

Butterfly, silk moth, frog, housefly and mosquito undergo metamorphosis while cow, human, hen and monkey do not undergo metamorphosis.

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

The stage of the embryo in which all the body parts can be identified is called a foetus. A human embryo becomes a foetus after about 8 weeks of pregnancy.

Difference between asexual and sexual reproduction:

Asexual reproduction	Sexual reproduction
In this type of reproduction, the offspring arises from a single parent.	The offspring arises from two parents of different sexes.
Example: Hydra, Amoeba, etc.	Example: Frog, human beings, etc.

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

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

The organisms which are produced asexually are genetically identical to the parent and are called clones. Dolly was born on 5th July 1996 and was the first mammal to be cloned.

Those animals which lay eggs are called oviparous animals. Examples - Hens and frog.