Science M.C.Q

Anatomically, the human arm, the flippers of seals, and the wings of the birds are the forelimbs containing similar bones.
These forelimbs have a common origin and similar anatomical features but have been modified to perform different functions.
Flippers allow the seal to swim, birds fly using their wings and humans perform a variety of functions using the arms.
Such structures are homologous to each other.
The wings of insects are anatomically different.

Evolution is a slow and steady process and organisms get adapted to environmental conditions in due course of time.
Accumulation of variations due to mutations in the genetic material over several generations forms new species.
Natural selection may operate differently in different geographic locations.
Eventually, different groups of new species will be formed from the same parent population.

Analogous structures are structures that are similar in unrelated organisms. The structures are similar because they evolved to do the same job, not because they were inherited from a common ancestor.

Sexual reproduction involves meiosis in gamete mother cells to form gametes and fusion of male and female gametes into zygote.

Analogous organs have a different basic design, so they indicate that the animals are not derived from a common ancestor.

Reduction in the weight of an organism due to starvation occurs due to scarcity of food in the environment. It is not genetically controlled.

All tall plants will be produced because tall genes are dominant over small genes.

Homologous organs are those which have same basic structure but different functions. Forelimbs of cow, a duck and a lizard have same basic structure but different functions.

The wings of a housefly and that of a sparrow are an example of analogous organs, as their basic structure is different, but they are used for the same purpose; i.e., flying.

Darwin proposed the theory of natural selection to explain the process of evolution.

Body size is an acquired trait, and cannot be passed on to the progeny.

According to Darwin's theory of evolution, variations, when accumulated over a long period of time lead to the origin of a new species.

Homologous organs are similar in origin but perform different functions. Both carrot as well as radish is underground roots. So, they belong to the homologous category.

Analogous organs are the opposite of homologous organs, which have similar functions but different origins.
An example of an analogous trait would be the wings of insects, bats and birds that evolved independently in each lineage separately after diverging from an ancestor without wings.

Homologous organs are the organs that have a similar origin and basic structure but different functions. Forelimbs of a cow, a duck and a lizard have a similar structure but different functions.
Hence, the correct option is Forelimbs of cow, a duck and a lizard.

A gene is a unit of heredity present on chromosomes that transfers characteristic from parents to their offsprings during reproduction.

Variations that impart reproductive or survival advantage to organisms are being favored during evolution.

Fossils found in the deepest layers of earth are the oldest ones. From these, scientists conclude that the extinction of an organism has occurred thousands of years ago.

Mendel is known as the 'father of genetics'.

The presence of homologous organs indicates that the two organisms are derived from the same ancestor.

In Mendel's experiments, characters like the nature of seed coat, flower colour, the position of flower, pod colour, stem height, etc. found in garden pea plants were studied.
These characters are referred to as phenotype.
Phenotype is the observable character and is the result of an expression of genotype.
Genotype refers to the genetic constitution.