Tag: introduction to genetics

Questions Related to introduction to genetics

When a cross is made between two parents with respect to a single character, it is called as

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

  1. Dihybrid

  2. Monohybrid

  3. Trihybrid

  4. None of these

Show answer
Correct Option: B
Explanation:
  • A monohybrid cross is a type of cross between two individuals with different alleles at one genetic locus of interest. 
  • The character(s) being studied in a monohybrid cross are governed by two or multiple alleles for a single locus.
  • A dihybrid cross is a cross between two pure lines (varieties, strains) that differ in two observed traits. In Mendelian sense, between the alleles of both these loci, there is a relationship of complete dominance - recessive.
  • Trihybrid cross is the mating of two individuals, organisms, or strains that have different gene pairs that determine three specific traits or in which three particular characteristics or gene loci are being followed.

A cross in which a single pair of contrasting characters is studied at a time is called as_____________

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

  1. Monohybrid cross

  2. Dihybrid cross

  3. Trihybrid cross

  4. Tetrahybrid cross

Show answer
Correct Option: A
Explanation:
  • A monohybrid cross is a mating between two individuals with different alleles at one genetic locus of interest. The cross involves a single pair of contrasting characters.

So, the correct answer is option A.

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

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

  1. Dihybrid cross

  2. Monohybrid cross

  3. Back cross

  4. Test cross

Show answer
Correct Option: B
Explanation:
  • The monohybrid cross-refers to inheritance of singe contrasting trait by two parents at a time. For example, a cross of tall (T) and dwarf (t) pea plants (TT x tt). Mendel observed that monohybrid cross between two pure breeding varieties yields $F _1$ generation which exhibits the dominant trait; although factor for a recessive trait is present in $F _1$ hybrids. Self-fertilization of $F _1$ generation obtains $F _2$ generation which exhibits both dominant and recessive traits in the 3:1 phenotypic ratio. This laid the foundation of the law of purity of gametes which states that the two factors for a trait, present together in a heterozygous individual, do not get mixed and are separated during gametogenesis. 

A breeding experiment studying a single trait is 

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

  1. Monozygous

  2. Dizygous

  3. Dihybrid

  4. Monohybrid

Show answer
Correct Option: D
Explanation:

Monohybrid cross refers to inheritance of a single contrasting trait by two parents at a time. For example, a cross of tall (T) and dwarf (t) pea plants (TT xtt). Dihybrid cross refers to inheritance of two pairs of contrasting characters by two parents at the same time. For example, a cross of two pea plants, one with yellow and round seeds (YYRR) and other with green and wrinkled seeds (yyrr). The term “monozygous” represents twins being developed from a single zygote. The first division in zygote produces two identical cells that independently develop into two embryos; monozygotic twins are produced. The term “dizygous” represent twins being developed from individual zygotes. Fertilization of two eggs by separate sperms produces two zygotes that independently develop into two embryos. Thus, the correct answer is the option D.

A husband and wife have normal vision but fathers of both of them were colour blind. Probability of their first daughter to be colour blind is

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

  1. 25%

  2. 50%

  3. 75%

  4. 0%

Show answer
Correct Option: D
Explanation:

Probability of their first (or any) daughter being colourblind is nil as the daughter of normal father can never be colourblind.

Biological unit controlling heredity is ___________.

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

  1. Genome

  2. Chromosome

  3. Genotype

  4. Gene.

Show answer
Correct Option: D
Explanation:

A.Genome – a set of chromosome in an organism in a body.

B.Chromosome – Dark coloured, small rod like structures, appear in the dividing nucleus is called Chromosome.

C.Genotype – It is the representation of an individual’s genetic constitution with respect to a single character or set of characters.

D.Gene - A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.

So, the correct option is ‘Gene’.

According to modern concept, Mendel's factor is called as_____________

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

  1. Chromosome

  2. Gene

  3. DNA

  4. Chromatid

Show answer
Correct Option: B
Explanation:
  • According to the modern concept, Mendel's factor is called a gene. Mendel believed that heredity is the result of discrete units of inheritance, and every single unit (or gene) was independent in its actions in an individual’s genome. According to this Mendelian concept, inheritance of a trait depends on the passing-on of these units. For any given trait, an individual inherits one gene from each parent so that the individual has a pairing of two genes.

What is the correct sequence from least complex to most complex in terms of the amount of information they carry?

I. Chromosomes
II. Base pair
III. Codon
IV. Gene

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

  1. I $\rightarrow $ II$\rightarrow $ III $\rightarrow $ IV

  2. II $\rightarrow $ III$\rightarrow $ I $\rightarrow $ IV

  3. III $\rightarrow $ II $\rightarrow $ I $\rightarrow $ IV

  4. II $\rightarrow $ III $\rightarrow $ IV $\rightarrow $ I

  5. II $\rightarrow $ IV $\rightarrow $ II $\rightarrow $ I

Show answer
Correct Option: D
Explanation:

A base pair (II) carries least information as at least three bases together (base triplet) make a codon (III) which in turn code for an amino acid. Genes (IV) are the stretch of DNA and each gene codes for a particular protein. Many genes are linearly arranged on a chromosome which means that chromosomes carry information for many proteins.

Therefore, the correct answer is option D.

When a cross is made between a tall plant with yellow seeds (Tt Yy) and a tall plant with green seeds (Tt yy), what is true regarding the proportions of phenotypes of the offsprings in F1 generation?
Proportion of Tall and Green         Proportion of Dwarf and Green 

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

  1. $\dfrac{3}{8}$ $\dfrac{1}{8}$

  2. $\dfrac{2}{8}$ $\dfrac{1}{8}$

  3. $\dfrac{1}{8}$ $\dfrac{3}{8}$

  4. $\dfrac{2}{8}$ $\dfrac{2}{8}$

Show answer
Correct Option: A

A tall plant was grown in nutrient deficient soil and remained dwarf. When it is crossed with dwarf plant then

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

  1. all hybrid plants are dwarf

  2. all hybrid plants are tall

  3. depend upon genotype of a tall plant

  4. 75% tall and 25% dwarf

Show answer
Correct Option: B
Explanation:

A tall plant was grown in nutrient deficient soil and remained dwarf .So , after crossed with dwarf plant then all hybrid plants are tall. Hybrid genotype is Tt.

Hence, correct option is B.