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].

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.

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.

Genes are stretches of DNA found on chromosomes of a cell. A gene contains information for making proteins in a “Cell”. A specific gene is located on a particular chromosome in individuals of a given species.

The acquired traits of organisms cannot be passed on to their future generations. If we breed some mice, all the progeny of mice will have tails, just like their parents. Now, if we cut the tails of these first-generation mice surgical and breed them, we will get new mice, all with full details. It has been observed that even after cutting the tails of mice for a number of generations, a tail-less mouse is never born. Actually, the cut tail of mice is an acquired trait which is never passed on to their progeny. This is because cutting the tails of mice does not change the genes of their reproductive cells or gametes.

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.

Acquired traits developed in response to the environment. The size of the body is an acquired trait because it can be changed on the availability of less or more food. The other three colour of eye and skin and nature of hair are inherited characters from the parents.

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.

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.

All variations in a species do not have equal changes of survival. Some of the variations may be so drastic that the new DNA copy cannot work with the cellular apparatus it inherits. Such a newborn cell dies soon. Depending on the nature of variations, different individual will have different kinds of advantage. Variations results from changes in genetic composition. Advantages of variations are selected by environmental factors. This leads to evolution and speciation. In asexual reproduction, there is minimum variation that is due to small errors in DNA copy.

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

The maleness of a child is determined by the Y-chromosome in zygote inherited from the father. If X-chromosome is inherited from the father, the zygote will develop into girl.

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.

The cross between RRyy and rrYY seeds will produce RrYy (round and yellow) seeds in F1 generation, because round and yellow are dominant traits.

The incorrect statement is [D] as fat molecules are not related to genes. On the other hand, genes contain information for making proteins in a cell. The proteins synthesized may be enzymes that catalyses biochemical reaction. The enzymes also control the process of making hormones. This explains why A, B and C are correct.

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.