Class 10 Science Chapter 8 MCQ

In the context of evolution, the use of feathers by birds for flying means that birds have evolved from reptiles. Dinosaurs have feathers but could not fly using them. Birds, later adapted the feathers for flight. Since, dinosaurs were reptiles, this means that birds have evolved from them.

Here, all the statements are correct. Hence, your answer will be option [D].

The number of sex chromosomes in the zygote of humans is one pair. It is not always a perfect pair. In females, it is perfect with two X-chromosomes. However, in males, there is one X-chromosome and one Y-chromosome.

When pure bred tall plant with phenotype (TT) crossed with short plant with phenotype (tt), the possible progeny in F2 generation: TT (1), tt (1) and Tt (2). Thus the ratio of pure tall (TT) to pure short (tt) is 1:1.

Evolution is a sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced. Since the evolution is of the living organisms, so it is also called “organic evolution”. All the plants and animals or organisms which we see today around us have evolved from some or the other ancestors that live on this earth long, long ago.

The two versions of a trait a sweet situated on copies of same chromosome. Each parent contributes one copy of the gene for a particular character. In the gamete however, only one copy is present due to reduction division. At the time of fusion, the diploid condition is maintained. Sex chromosomes carry genes for sexual characters.

The genotype of the tall parent can be depicted as TtWW. It is because T is the gene for tallness, t for dwarfness; W is the gene for violet flowers, while w is for white flowers. Thus, T and W are dominant genes, whereas t and w are recessive genes.

Accumulation of variation over several generation forms new species. Genetic drift accumulates different changes in sub-populations of a species. Also, natural selection may also operate differently in the different geographic location. Eventually different groups of new species will be formed.

Father is responsible for the sex of the baby boy or girl which is born. If the husband contributes a “Y sex chromosome” at fertilization through his sperm, then the baby born will be a boy. This means that it is the sex chromosome contributed by husband which decides the sex of the baby which the wife will give birth to. Thus, husband is responsible for the sex of the baby (boy or girl) which is born.

Two individuals of a species share maximum number of common characters. A species is a population of organisms consisting of similar individuals which can breed together and produce fertile offspring.

Here, all the statements are correct. Hence, your answer will be option [D].

A trait of an organism is influenced by both maternal and paternal DNA. It is passed down from one generation to another through genes found on the chromosomes. During sexual reproduction, both mother and father passed their genes to their children, thus determining their traits or characteristic features.

Radish and carrot represent homologous structures as they have the same structure or basic design through they are different species.

The new combination in F2 progeny will be round yellow and wrinkled green. The phenotype ratio of 9 : 3 : 3 : 1 is obtained. Round yellow : Round green : Wrinkled yellow : Wrinkle green = 9 : 3 : 3 : 1

New species may be formed if the DNA changes are severe enough, such as a change in the number of chromosomes. This leads to new variations.

In human males, one pair called the “Sex chromosomes” are unpaired. Here, one is a normal sized X-chromosome while other is a short Y-chromosome. Women have a perfect pair of sex chromosomes, both called X.

In F1 generation, the cross between “TT” and “tt” will result into all tall plants. Thus, tallness is the dominant trait or character. Whenever the two traits of a character are crossed, the F1 plants show only one of the traits. This trait is called the dominant trait. The other trait (dwarfness in this case) that does not express itself in F1 generation is called the recessive trait.

The nature of the cross will be cross fertilization. Fertilizing a plant using pollen from another plant of the same species is cross fertilization. Double fertilization is a complex fertilization mechanism of flowering plants. It involves fusion of a male and female gamete. Self-pollination is a form of pollination that occur in a flower that has both stamen and carpel.

Exchange of genetic material take place in sexual reproduction as genes of two parents are involved. In asexual reproduction, no exchange of genetic material take place as a single parent is involved. Budding and vegetative reproduction are types of “Asexual Reproduction”. So, there is no exchange of genetic material.

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

F2 generation can be obtained by allowing flowers on the plants of F1 generation to be self-pollinated.

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

The accumulation of “heat resistant variation” or trait in some bacteria will ensure its survival, even when the temperature in its environment rises to much due to a heat wave or some other reasons. On the other hand, the bacteria which did not have these variations to withstand heat would not survive under these circumstances and die.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D]. tors that live on this earth long, long ago.