Science M.C.Q

The two versions of a trait, which are brought in by the female and male gametes are situated on the copies of the same chromosome.

Blood proteins A and B are codominant traits, as neither of these is able to dominate the other completely.

Explanation:
The number of chromosomes present in a sex cell of a human being would normally be 23.

Scientists believe that all life originated in sea water.

Evolution is the sequence of gradual changes, which take place in primitive organisms over millions of years, due to which new species are formed.

In progeny, all plants obtained will be tall because tallness is the dominant trait, while dwarfism is the recessive trait.

Trilobites were marine arthropods which were common 400–600 millions years ago.

Mendel used pea plants for his experiments on heredity.

Fats are not synthesised by genes present on chromosomes.

Spinach has not been produced from wild cabbage by the process of artificial selection.

The organs which perform a similar function, but have different basic structures are called analogous organs.
For example: wings of insects and birds are analogous.

In the context of evolution, it means that birds have evolved from reptiles.

Oxygen was absent in early earth atmosphere.

The number of sex chromosomes in the zygote of humans is two-- XX in females and XY in males.

Wings of an insect and forelimbs of a bird are analogous organs, as they have different structures but perform the same function of flying.

Mendel ensured that he used pure breeding plants for his experiments by letting each variety self-pollinate for several generations.

The science of heredity is known as genetics.

The theory of evolution of species by natural selection was given by Charles Darwin in his book The Origin of Species.

Butterfly and bat wings cannot be considered homologous organs as they have different basic designs.

Snub nose is an inherited trait, and can be can be passed on to the progeny.

The organs that perform different functions but have the same basic structure are known as homologous organs.
For example: forelimbs of humans and lizards are homologous.

All variations in a species do not have an equal chance of survival. Variations may either be beneficial or harmful to the species.

Earliest members of the human species came from Africa.

Scarred chin is an acquired trait, which an individual gets due to an accident. It cannot be passed on to the progeny.

The exchange of genetic material occurs during meiosis, that takes place in the gametes of sexually reproducing organisms.

In evolutionary terms, we have more in common with a chimpanzee because both human beings and chimpanzees had a common ancestor, long time ago.

According to scientists, aves have evolved from reptiles.

The characteristic (or trait) in an organism that is visible is called its phenotype.

Palisade cells of leaves are somatic cells. Each gamete produced by the plant will have half the number of chromosomes present in a palisade cell i.e. 14 chromosomes.

In humans, XY combination of chromosomes represents a male.

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.

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.

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.

A trait in an organism is influenced by both maternal and paternal DNA. This is because in zygote, one half of the chromosomes is contributed by the mother, and the other half by the father.

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

The sex of a child is determined by the Y chromosome that is present in a sperm.

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.

Explanation:
Mendel is known as the 'father of genetics'.