Assertion & Reason Test: Heredity & Evolution - 2


15 Questions MCQ Test Science Class 10 | Assertion & Reason Test: Heredity & Evolution - 2


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Attempt Assertion & Reason Test: Heredity & Evolution - 2 | 15 questions in 30 minutes | Mock test for Class 10 preparation | Free important questions MCQ to study Science Class 10 for Class 10 Exam | Download free PDF with solutions
QUESTION: 1

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Fossils are remains of dead organisms.

Reason : It is helpful in the study of evolution.

Solution: Fossils are remains of hard parts of the past individuals in the strata of earth. It helps in tracing evolutionary pathways.
QUESTION: 2

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Learning a skill such as dance and music is an acquired trait.

Reason : Acquired traits develop in the lifetime of an individual and do not pass to the progeny.

Solution: Trails which develop in the lifetime of an individual and do not pass to the progeny are called acquired traits. Learning a skill such as dance/music/loss of body parts/weight etc are examples of acquired traits.
QUESTION: 3

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Mendel selected the pea plant for his experiments.

Reason : Pea plant is cross-pollinating and has unisexual flowers.

Solution: Mendel selected garden pea plant for his experiments because of the following characteristics

(i) The flowers of this plant are bisexual.

(ii) They are self-pollinating, and thus, self and cross pollination can easily be performed.

(iii) The different physical characteristics were easy to recognise and study.

(iv) They have a shorter life span and the plants are easier to maintain.

QUESTION: 4

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Although living organisms always arise from other living organisms, life should certainly have had a beginning.

Reason : The study of the conditions and the mechanisms involved in the creation of most primitive living structures on earth is actually the problem of origin of life.

Solution: Life originates from pre-existing life forms and the process is termed as biogenesis. According to Oparin and Haldane’s theory of biochemical origin of life, life originated spontaneously from non-living matter in the primitive atmosphere of earth (abiogenesis). Assertion is correct.

The primitive reducing atmosphere of Earth was rich in water vapour, carbon monoxide, carbon dioxide, nitrogen and hydrogen. UV light, high temperature and lightning served as sources of energy for chemical reactions between above-mentioned gases to form simple organic compounds which in turn produced more complex organic compounds and finally the first living cell. The reducing atmosphere and absence of life on primitive Earth favoured the origin of life which is not possible in present day oxidizing atmosphere because the compounds are readily oxidized as soon as they are formed. Thus, now life is not originating spontaneously but only biogenesis exists. Reason is correct.

QUESTION: 5

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : We have lost all the direct evidence of the origin of life.

Reason : The persons responsible for protecting evidence were not skilled.

Solution: During the profound changes that have been taking place since the remote past, we have lost the direct evidence of the origin of life. Due to these changes, the scientists, though skilled, were not able to protect the evidence.
QUESTION: 6

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : DNA finger p rin tin g is a method in which polymerase chain reaction followed by DNA probe is used.

Reason: A DNA fingerprint is inherited and therefore, resembles that of parents.

Solution: DNA fingerprinting is also called DNA profiling. It is a laboratory technique used to identify the individuals with the characteristics of their DNA. It is used to solve some crime mysteries like murder, rape etc. Usually, the samples (e.g., blood, semen,saliva) that are available for the testing are small. Hence, polymerase chain reaction is used to amplify the amount of DNA present in the sample. Hence, the assertion is correct.

DNA fingerprints have an inheritable quality. The pattern types of the DNA fingerprints are often genetically inherited from the parents to the offsprings. Hence, the DNA fingerprint resembles that of parents. The reason is correct but it is not a correct explanation of the assertion. Thus, the correct answer is option B.

QUESTION: 7

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : The sex of a child is determined by the mother.

Reason : Humans have two types of sex chromosomes: XX and XY.

Solution: Human males have a XY genotype and form two types of sperms carrying either X or Y sex chromosomes. A zygote formed by fusion of sperm with X and an egg cell results in a female child, whereas the fusion of a Y sperm leads to a male child.
QUESTION: 8

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Ear muscles of the external ear in m a n are poorly developed.

Reason: These muscles are useful which move the external ear freely to detect sound efficiently.

Solution: The external ear in humans is an example of vestigial organs and is poorly developed. It consists of pinna or auricles whose muscles are useless for humans. But in many mammals, these muscles are used to move their pinna to collect the sound waves and focus their hearing in a particular direction. In the case of human pinna, this kind of function is absent. It is just protective and increases the efficiency of hearing.

So the correct option is C.

QUESTION: 9

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Chromosomes are known as hereditary vehicles.

Reason : The chromosomes are capable of self reproduction and maintaining morphological and physiological properties through successive generations.

Solution: Chromosomes are short, thick, condensed rod-like structures present in the nucleus which distribute genetic information to the daughter cells. They are capable of self-replication before the cell division and thus are passed to the next generation. They contain genes on them which control the morphological and physiological properties of cells. Thus, the correct answer is option A.
QUESTION: 10

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Mutation is sudden change in the genetic material.

Reason : Variation is useful for the survival of species over time.

Solution: Sudden change in genetic character is known as mutation. Mutation is the phenomenon of alterations to DNA. This results in the development of new characteristics that are capable of being inherited. It results either due to error during DNA replication or damage to DNA.
QUESTION: 11

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Human ancestors never used their tails and so the tail expressing gene has disappeared in them.

Reason : Lamarck’s theory of evolution is popularly called the theory of continuity of germplasm.

Solution: According to Lamark’s theory, continuous disuse of organs makes them weak. The theory of continuity of germplasm was given by Weismann.
QUESTION: 12

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : The sex of the children will be determined by chromosome received from the father.

Reason : A human male has one X and one Y -chromosome.

Solution: If a child inherits X -chromosome from the father will be a girl and one who inherits a Y-chromosome will be a boy.
QUESTION: 13

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Dominant allele is an allele whose phenotype expresses even in the presence of another allele of that gene.

Reason : It is represented by a capital letter, e.g. T.

Solution: Hemizygous condition refers to the presence of a single copy on a gene rather than two as are present for mendelian traits. Since the dominance-recessive relationship is applied when a trait is exhibited by two copies of same or different alleles of a gene, both recessive and dominant traits are expressed in a homozygous condition which is characterized by the presence of two copies of same alleles for a gene in an individual (TT or tt). The presence of contrasting alleles of a gene in an individual is referred to as heterozygous condition. For example, a plant with genotype “Tt” is heterozygous for the gene of height. Since expression of a recessive allele is masked by the presence of the dominant allele in heterozygous genotype, the only dominant trait is expressed by them irrespective of the presence of both dominant and recessive alleles.
QUESTION: 14

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : A geneticist crossed two pea plants and got 50% tall and 50% dwarf in the progeny.

Reason : One plant was heterozygous and the other was dwarf.

Solution: In the given cross, geneticists found 50% tall and 50% dwarf plants. The dwarf phenomenon is the recessive character which can only be expressed in homozygous condition. Here the cross shows that 50% of the population of the plant are dwarfs. Thus it can be concluded that one of the parent plants of this plant must be heterozygous.

Let, the genotype of the heterozygous tall plant it Tt. Here T stands for tall and t expresses the dwarf phenomenon. As T is dominant over t it appears phenotypically.

The genotype of dwarf plant tt

Possible gametes come from the heterozygous tall plant and the homozygous dwarf are T, t and t, t respectively.

The cross is shown in the checkerboard:

The cross shows a 50% tall plant and 50% dwarf plant.

So, the correct answer is “Option A”, both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

QUESTION: 15

Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion: Traits like eye colour or height are inherited traits.

Reason : Inherited traits are not transferred from parents to young ones.

Solution: Eye colour and height are genetically inherited traits, as these are expressed by genes. Inherited traits are the traits which are transferred from parents to young ones. Acquired traits are the characters that are acquired by the individual during its lifetime. These traits cannot be inherited. For example, if a wrestler develops large muscles due to his training program that does not mean it will be passed on to his offspring.
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