Tag: introduction to genetics

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Multiple choice botany classical genetics variation and its type natural selection introduction to genetics

The most likely reason for the development of resistance against pesticides in insects damaging crops is:

  1. genetic recombination

  2. directed mutations

  3. acquired heritable changes

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. Cases of resistance have been reported in all classes of pests (i.e. crop diseases, weeds, rodents, etc.), with 'crises' in insect control occurring early-on after the introduction of pesticide use in the 20th century. The Insecticide Resistance Action Committee (IRAC) definition of insecticide resistance is 'a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species'. Although the evolution of pesticide resistance is usually discussed as a result of pesticide use, it is important to keep in mind that pest populations can also adapt to non-chemical methods of control.
So the correct option is 'acquired heritable changes'.
Multiple choice biology variation variation and its type natural selection introduction to genetics

Which of the following is not heritable?

  1. Point mutation

  2. Chromosomal mutation

  3. Somatic mutation

  4. Gene mutation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a sequence of DNA or RNA. Each triplet codon corresponds to an amino acid when translated to protein. When one of these codons is changed by a point mutation, the corresponding amino acid of the protein is changed.
  • Chromosomal mutation is presence or absence of one or more set of chromosomes in a cell or a structural abnormality in the normal set of chromosomes.
  • Somatic mutation is the occurrence of a mutation in the somatic cells (cells other than sperm and egg) of the organism. These are frequently caused by environmental factors like exposure to UV rays or to certain chemicals. 
  • Gene mutation is a permanent alteration in the DNA sequence that makes up a gene. They are of two types: Hereditary mutations (inherited from parents) and Acquired mutation (occur at some time during a person's life).
So, the correct answer is 'Somatic mutation'

Multiple choice biology variation variation and its type natural selection introduction to genetics

There is an inbuilt tendency to variation during reproduction, because of errors in DNA copying and as a result of sexual reproduction.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sexual reproduction results in more variation than the asexual reproduction. During sexual reproduction, there are chances of errors occurring during DNA copying. Crossing over also takes place during sexual reproduction. All these ultimately result in the variation. This variation helps survival in species and also supports diversity in the course of evolution.

Thus, the correct answer is option A.

Multiple choice biology variation variation and its type natural selection introduction to genetics

To be evolutionary successful, the mutation must occur in 

  1. Somatoplasm

  2. Germplasm

  3. Karyolymph/zygote

  4. Ergastoplasm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total of specialized protoplasm other than germplasm in individual body or protoplasm of somatic cells is termed as somatoplasm. Germplasm is protoplasm of germ cells (egg and sperm cells) or any living tissues with the capability of generating new organisms. The germplasm is inherited from parents to offspring along with gametes; thus any mutation in germplasm is passed to progeny which is a requisite for successful mutation; option B is correct. Since somatoplasm is not passed to offspring, any mutation in it affects that individual only and is not passed to offspring which makes option A incorrect. The liquid phase of cell nucleus which harbours the nucleolus and chromatin and other structures is called as karyolymph. Similarly, the mutation in zygote affects single individual that develops from that zygote. Option C is incorrect. The granular endoplasmic reticulum that has studded ribosomes on its surface is called as ergastoplasm which is not inherited to offspring and thus is not suitable for successful mutation; option D is incorrect. Correct option B is correct. 

Multiple choice biology variation variation and its type natural selection introduction to genetics

Which type of variation is inherited?

  1. Somatic variation

  2. Germinal variation

  3. Both A and B

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The variation which affects the germinal or reproductive cells is called as germinal variation. It is heritable and genetically significant. It provides raw materials for evolution.
Multiple choice biology variation variation and its type natural selection introduction to genetics

Which mutation/variation is not hereditary _____________.

  1. Genetic

  2. Gametic

  3. Somatic

  4. Germinal.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A sudden, inheritable, discontinuous variation due to change in chromosomes and genes is called Mutation. It is hereditary. Mutations in somatic cells are not hereditary.

So, the correct option is ‘somatic’.

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Choose the correct answer from the alternatives given.


In a monohybrid cross between two heterozygous individuals, percentage of  re homozygous individuals obtained in $F 1$ generation will be ________.

  1. 25%

  2. 50%

  3. 75%

  4. 100%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a monohybrid cross between two heterozygotes (Tt x Tt), the F1 genotypes are 1 TT, 2 Tt, and 1 tt. The homozygous individuals are TT and tt (1+1=2 out of 4), which is 50 percent.

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Mendel formulated the law of purity of gametes on the basis of

  1. monohybrid cross

  2. dihybrid cross

  3. test cross

  4. back cross
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A gamete may carry either the dominant or the recessive factor but not both as we find in F1 individuals. This is why it is called either as 'principle of segregation' or as 'law of purity of gametes'. This concept of segregation is often called Mendel's first principle. The alleles of contrasting characters selected in the monohybrid cross will show exact Dominance and Recessive relationships. Monohybrid cross refers to  mating between two organisms with different variations at one genetic chromosome of interest. The character(s) being studied in a monohybrid cross are governed by two or multiple variations for a single locus.

So, the correct answer is 'monohybrid cross'.

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics

Which of the following is considered as physical and chemical unit of heredity?

  1. Gene

  2. Chromosome

  3. Nucleotide

  4. Codon

  5. Chromatid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A gene is a locus (or region) of DNA which is made up of nucleotides and is the molecular unit of heredity. It controls the development and function of all organs and all working systems in the body. Genes are passed from parent to offspring; the combination of these genes affects all aspects of the human body, from eye and hair colour to how well the liver can process toxins. 

Therefore, the correct answer is option A.