Mendelism Questions in English

(A) In genetics,an organism is said to be $Homozygous$ for a particular trait when it carries two identical alleles for that gene (e.g.,$TT$ or $tt$).
If the alleles are different (e.g.,$Tt$),the organism is said to be $Heterozygous$.
$Dioecious$ and $Monoecious$ are terms related to the sexual reproductive system of plants,not the genetic composition of alleles.

(D) hybrid plant resulting from two alternative alleles (e.g.,$T$ and $t$) is known as a heterozygous individual. In genetics,an organism is called heterozygous if it carries two different alleles for a specific gene locus. Therefore,the correct term for a plant with two alternative alleles is heterozygous.

(A) The correct answer is $A$. Mendel studied $7$ pairs of contrasting traits in pea plants. The character 'Trichomes-Glandular or non-glandular' was not one of them.

$1$. Seed shape	Round $(R)$ / Wrinkled $(r)$
$2$. Seed colour	Yellow $(Y)$ / Green $(y)$
$3$. Flower colour	Violet $(V)$ / White $(v)$
$4$. Pod shape	Inflated $(I)$ / Constricted $(i)$
$5$. Pod colour	Green $(G)$ / Yellow $(g)$
$6$. Flower position	Axial $(A)$ / Terminal $(a)$
$7$. Stem height	Tall $(T)$ / Dwarf $(t)$

(D) Gregor Johann Mendel conducted his hybridization experiments on garden pea ($Pisum$ $sativum$) for $7$ years.
These experiments were carried out during the period from $1856$ to $1863$.
Therefore,the correct option is $(d)$.

(D) : Mendel considered the following $7$ pairs of contrasting characters in his experiments on pea plants:

$1$. Seed shape	Round $(R)$ / Wrinkled $(r)$
$2$. Seed colour	Yellow $(Y)$ / Green $(y)$
$3$. Flower colour	Violet $(V)$ / White $(v)$
$4$. Pod shape	Inflated $(I)$ / Constricted $(i)$
$5$. Pod colour	Green $(G)$ / Yellow $(g)$
$6$. Flower position	Axial $(A)$ / Terminal $(a)$
$7$. Stem height	Tall $(T)$ / Dwarf $(t)$

Mendel did not use pod length as a character in his experiments. Therefore, the correct option is $D$.

(B) Mendel selected $7$ pairs of true-breeding contrasting characters in pea plants $(Pisum \text{ } sativum)$ for his hybridization experiments. These characters are summarized in the table below:

$1$. Character: Seed shape (Dominant: Round,Recessive: Wrinkled)

$2$. Character: Seed colour (Dominant: Yellow,Recessive: Green)

$3$. Character: Flower colour (Dominant: Violet,Recessive: White)

$4$. Character: Pod shape (Dominant: Inflated,Recessive: Constricted)

$5$. Character: Pod colour (Dominant: Green,Recessive: Yellow)

$6$. Character: Flower position (Dominant: Axial,Recessive: Terminal)

$7$. Character: Stem height (Dominant: Tall,Recessive: Dwarf)

(A) test cross is performed to determine the genotype of an $F_2$ plant showing a dominant phenotype.
In a typical test cross,an organism with a dominant phenotype whose genotype is unknown is crossed with an individual that is homozygous recessive for the trait being investigated.
The resulting progeny can be analyzed to determine the genotype of the parent organism.
If the progeny shows a $1:1$ ratio of dominant to recessive phenotypes,the parent was heterozygous $(Aa)$.
If all progeny show the dominant phenotype,the parent was homozygous dominant $(AA)$.

(C) The correct answer is $C$.
Test cross is performed to determine the unknown genotype of an organism showing a dominant phenotype.
In a typical test cross,an organism with a dominant phenotype is crossed with an individual that is homozygous recessive for the traits being investigated.
This method allows researchers to determine whether the dominant phenotype is homozygous or heterozygous by analyzing the phenotypic ratio of the offspring.
For example,in a monohybrid test cross,if the $F_1$ hybrid $(Tt)$ is crossed with a homozygous recessive parent $(tt)$,the resulting offspring will show a $1:1$ ratio of dominant to recessive phenotypes if the parent was heterozygous.

(A) : $A$ test cross is performed to determine the genotype of an organism showing the dominant phenotype. In a typical test cross,an organism with a dominant phenotype whose genotype is unknown is crossed with an individual that is homozygous recessive for the trait being investigated. The resulting progeny can be analyzed to determine whether the parent was homozygous dominant or heterozygous. This method is more precise than self-crossing for genotype determination.

(C) : $A$ test cross is performed to determine the unknown genotype of an organism showing a dominant phenotype.
In a typical test cross, the organism with the dominant phenotype is crossed with a homozygous recessive parent.
This method allows researchers to identify whether the dominant individual is homozygous or heterozygous by analyzing the phenotypic ratio of the offspring.
If the offspring show a $1:1$ ratio of dominant to recessive phenotypes, the parent was heterozygous.
If all offspring show the dominant phenotype, the parent was homozygous dominant.

(C) The correct method to determine the genotype of a hybrid (or an individual showing a dominant phenotype) is a test cross.
In a test cross,an individual of unknown genotype is crossed with a homozygous recessive parent.
Therefore,crossing an $F_1$ hybrid with its recessive parent allows us to identify the genotype of the $F_1$ individual.
Option $C$ is the most accurate description of this process in the context of genetic analysis.

(D) The correct answer is $D$. $A$ test cross is performed to determine the unknown genotype of an organism showing a dominant phenotype.
In a typical test cross, an organism with a dominant phenotype is crossed with an individual that is homozygous recessive for the trait being investigated.
By analyzing the phenotypic ratio of the resulting progeny, the genotype of the parent organism can be determined.
For example, if an organism with a dominant trait (genotype $Tt$) is crossed with a homozygous recessive individual $(tt)$, the offspring will reveal whether the parent was homozygous dominant $(TT)$ or heterozygous $(Tt)$.

(C) true breeding plant is one that,when self-pollinated,consistently produces offspring with the same traits as the parent.
This occurs because the plant is near homozygous for the traits in question.
Therefore,it maintains its genetic purity over successive generations.
Option $C$ is the correct definition.

(B) In $1900$,three scientists independently rediscovered Mendel's work on the inheritance of characters.
These scientists were Hugo de Vries (from the Netherlands),Carl Correns (from Germany),and Erich von Tschermak (from Austria).
They recognized the significance of Mendel's laws of inheritance,which had remained largely ignored for several decades after their initial publication in $1866$.

(C) Gregor Johann Mendel,often referred to as the 'Father of Genetics',conducted experiments on pea plants ($Pisum$ $sativum$).
He proposed the fundamental laws of inheritance,which include the Law of Dominance,the Law of Segregation,and the Law of Independent Assortment.
These laws explain how traits are passed from parents to offspring.

(B) Genes that code for a pair of contrasting traits are called $Alleles$ (or $Allelomorphs$).
$Alleles$ are slightly different forms of the same gene that occupy the same locus on homologous chromosomes.
For example,in pea plants,the gene for height has two $Alleles$: one for tall $(T)$ and one for dwarf $(t)$.

(C) Punnett square is a graphical representation used to predict the probability of all possible genotypes of offspring in a genetic cross.
It helps in visualizing the segregation of alleles and their random fertilization to form zygotes.
By listing the gametes of both parents on the axes,one can determine the genotypic and phenotypic ratios of the progeny.
Therefore,it accounts for all possible combinations of alleles,not just dominant or recessive ones.

(D) In Mendelian genetics,a pure tall plant is represented by the genotype $TT$ and a dwarf plant by $tt$.
When these are crossed,the $F_1$ generation consists of heterozygous tall plants with the genotype $Tt$.
$A$ cross between an $F_1$ tall plant $(Tt)$ and a dwarf plant $(tt)$ is known as a test cross.
The Punnett square for this cross $(Tt \times tt)$ is as follows:
- Gametes from $Tt$: $T$ and $t$.
- Gametes from $tt$: $t$ and $t$.
- Offspring genotypes: $Tt, Tt, tt, tt$.
This results in a phenotypic ratio of $50\%$ tall $(Tt)$ and $50\%$ dwarf $(tt)$.

(C) Gregor Mendel studied seven pairs of contrasting traits in pea plants.
According to his findings,the dominant and recessive traits for flower position are:
$1$. Axillary position is the dominant trait.
$2$. Terminal position is the recessive trait.
Therefore,the option stating 'Flower position: Terminal (dominant),Axillary (recessive)' is incorrect because it reverses the actual biological relationship.

(D) In genetics,when two parent organisms are crossed,the resulting offspring generation is called the first filial generation.
This is abbreviated as the $F_1$ generation,where '$F$' stands for 'filial' (meaning son or daughter in Latin).
Therefore,both 'First filial generation' and '$F_1$ generation' refer to the same concept.
Thus,the correct option is $D$.

(D) According to Mendel's experiments on the garden pea plant $(Pisum \text{ } sativum)$, there are seven pairs of contrasting traits.
Among the given options:
$1$. Wrinkled seed shape is a recessive trait (Round is dominant).
$2$. Green seed colour is a recessive trait (Yellow is dominant).
$3$. Yellow pod colour is a recessive trait (Green is dominant).
$4$. Axial flower position is a dominant trait (Terminal is recessive).
Therefore, the correct option is $D$.

(A) test cross is a genetic cross between an individual of unknown genotype (showing a dominant phenotype) and a homozygous recessive individual.
It is used to determine the genotype of the individual showing the dominant trait.
If the offspring show a $1:1$ ratio of dominant to recessive phenotypes,the parent is heterozygous.
If all offspring show the dominant phenotype,the parent is homozygous dominant.

(A) test cross is a genetic cross between an individual of unknown genotype and a homozygous recessive individual.
It is primarily used to determine the genotype of an organism that exhibits a dominant phenotype.
If the offspring show both dominant and recessive traits,the parent was heterozygous.
If all offspring show the dominant trait,the parent was homozygous dominant.
Therefore,a test cross is used to identify the genotype.

(B) Mendel studied seven pairs of contrasting traits in pea plants.
According to his findings:
$1$. Seed colour: Yellow is dominant,Green is recessive.
$2$. Flower colour: Violet is dominant,White is recessive.
$3$. Seed shape: Round is dominant,Wrinkled is recessive.
$4$. Flower position: Axial is dominant,Terminal is recessive.
In option $B$,the traits are swapped; Violet is the dominant flower colour,while White is the recessive one. Therefore,option $B$ is the incorrect pair.

(C) In a haploid organism,the genome consists of only one set of chromosomes $(n)$.
Since there is only one copy of each gene present in the cell,there is no second allele to mask the expression of a recessive allele.
Therefore,any allele present,whether dominant or recessive,will be expressed phenotypically.
This is why haploid organisms are ideal for genetic studies involving mutations,as even recessive mutations are immediately expressed.

(D) Gregor Mendel's success in his experiments on pea plants was primarily due to his systematic approach.
$1$. He maintained accurate records of all observations and performed a statistical/quantitative analysis of the data.
$2$. He focused on one or a few traits at a time,which simplified the analysis of inheritance patterns.
$3$. He chose true-breeding pea plant varieties.
Therefore,the most significant methodological reason among the options provided is that he considered one trait at a time (or a limited number of traits) to avoid complexity.

(B) Gregor Johann Mendel is known as the father of genetics. He performed hybridization experiments on garden peas ($Pisum$ $sativum$) for seven years $(1856-1863)$ and proposed the laws of inheritance in living organisms.

(B) In genetics,$Mendel$ referred to the contrasting forms of a character as 'contrasting traits'. These traits are controlled by different forms of a gene,which are known as alleles (or allelomorphs). Therefore,a pair of contrasting traits is represented by a pair of alleles.

(A) According to the law of dominance,a dominant allele is one that expresses its phenotypic effect in both the homozygous $(AA)$ and heterozygous $(Aa)$ conditions.
In the heterozygous condition,the dominant allele masks the expression of the recessive allele.
Therefore,the correct option is $A$.

(A) According to Mendel's Law of Segregation,the two alleles of a gene pair segregate from each other during the formation of gametes.
In meiosis,this segregation of homologous chromosomes occurs during $Anaphase-I$.
During $Anaphase-I$,the homologous chromosomes separate and move towards opposite poles,which ensures that each gamete receives only one of the two alleles.
Therefore,the correct phase for the segregation of Mendelian factors is $Anaphase-I$.

(D) An organism is said to be $Homozygous$ for a trait when it carries two identical alleles for that specific gene (e.g., $TT$ or $tt$).
In contrast, an organism is $Heterozygous$ if it carries two different alleles for a gene (e.g., $Tt$).
Therefore, the correct term for an organism with two identical alleles is $Homozygous$.

(C) Mendel studied $7$ pairs of contrasting traits in garden pea $(Pisum \text{ } sativum)$.
According to his findings:
$1$. Seed color: Yellow is dominant, Green is recessive.
$2$. Flower position: Axial is dominant, Terminal is recessive.
$3$. Pod color: Green is dominant, Yellow is recessive.
$4$. Seed shape: Round is dominant, Wrinkled is recessive.
Therefore, among the given options, 'Green pod color' is the dominant trait.

(D) In Mendel's experiments on pea plants,the round seed shape is dominant over the wrinkled seed shape. The wrinkled phenotype is caused by the mutation in the gene encoding the starch-branching enzyme $(SBE)$. Due to the deficiency or lack of this enzyme,the conversion of sugar into starch is inefficient,leading to the accumulation of sugar. This high sugar concentration causes the seeds to absorb more water during development and subsequently lose it during maturation,resulting in the wrinkled appearance of the seeds.

(D) Mendel studied $7$ pairs of contrasting traits in pea plants.
Among these,the recessive traits are:
$1$. Wrinkled seed shape
$2$. Green seed color
$3$. White flower color
$4$. Constricted pod shape
$5$. Yellow pod color
$6$. Terminal flower position
$7$. Dwarf plant height.
Therefore,among the given options,'Green seed color' is a recessive trait.

(B) Gregor Mendel studied $7$ pairs of contrasting traits in pea plants $(Pisum \text{ } sativum)$.
These $7$ traits are controlled by genes located on $4$ different chromosomes.
Specifically, these genes are located on chromosome numbers $1, 4, 5,$ and $7$ of the pea plant.
Therefore, the correct answer is $4$.

(A) $Reciprocal$ $cross$ is a breeding experiment designed to test the role of parental sex on a given inheritance pattern. In this cross, two sets of crosses are made:
$1$. In the first cross, a male of genotype $A$ is crossed with a female of genotype $B$.
$2$. In the second cross, a male of genotype $B$ is crossed with a female of genotype $A$.
Since the source of gametes (sex of the parent) is reversed, it is termed a $Reciprocal$ $cross$.

(C) test cross is a genetic cross between an individual with an unknown genotype (usually showing the dominant phenotype) and an individual that is homozygous recessive for the trait in question.
Its primary purpose is to determine the genotype of the individual displaying the dominant phenotype.
If the individual is homozygous dominant,all offspring will show the dominant trait.
If the individual is heterozygous,the offspring will show a $1:1$ ratio of dominant to recessive phenotypes.
Therefore,crossing an $F_1$ hybrid with a double recessive genotype is the definition of a test cross.

(D) The process of crossing an $F_1$ hybrid with its recessive parent is known as a $Test \ Cross$.
This cross is specifically used to determine the genotype of an individual showing a dominant phenotype.
If the offspring of the test cross show a $1:1$ ratio of dominant to recessive phenotypes,the individual is heterozygous.
If all offspring show the dominant phenotype,the individual is homozygous dominant.

(A) test cross is a cross between an individual with a dominant phenotype (whose genotype is unknown) and a homozygous recessive individual.
If the offspring show a $1:1$ ratio of dominant to recessive phenotypes,the parent is heterozygous.
If all offspring show the dominant phenotype,the parent is homozygous dominant.
Therefore,a test cross is the standard method to determine the genotype of an organism showing a dominant trait.

(B) Gregor Mendel selected $7$ pairs of contrasting traits in pea plants ($Pisum$ $sativum$) for his hybridization experiments.
These traits are:
$1$. Stem height (Tall/Dwarf)
$2$. Flower color (Violet/White)
$3$. Flower position (Axial/Terminal)
$4$. Pod shape (Inflated/Constricted)
$5$. Pod color (Green/Yellow)
$6$. Seed shape (Round/Wrinkled)
$7$. Seed color (Yellow/Green)
Among the given options,'Pod length' was not one of the $7$ traits studied by Mendel.

(C) true-breeding plant is one that,through continuous self-pollination,produces offspring with the same traits generation after generation.
Such plants are homozygous for their traits,meaning they carry identical alleles for the genes in question,which ensures that they produce offspring identical to themselves.

(B) Gregor Mendel studied $7$ pairs of contrasting traits in pea plants $(Pisum \text{ } sativum)$.
These traits are:
$1$. Stem height: Tall/Dwarf
$2$. Flower colour: Violet/White
$3$. Flower position: Axial/Terminal
$4$. Pod shape: Inflated/Constricted
$5$. Pod colour: Green/Yellow
$6$. Seed shape: Round/Wrinkled
$7$. Seed colour: Yellow/Green
Trichomes (glandular or non-glandular) were not among the $7$ traits studied by Mendel.

(A) Gregor Johann Mendel conducted his hybridization experiments on garden peas $(Pisum)$ $\text{sativum}$ for a period of $7$ years.
These experiments were carried out from $1856$ to $1863$.
During this time, he proposed the laws of inheritance in living organisms.

(D) The correct statement is that the Punnett square was developed by a British geneticist, Reginald $C$. Punnett.
- Transduction was discovered by Joshua Lederberg and Norton Zinder in $1952$, not $S$. Altman.
- The term "linkage" was coined by Thomas Hunt Morgan, not Franklin Stahl.
- Spliceosomes are involved in $RNA$ splicing (post-transcriptional modification), not in translation.

(B) In genetics,a test cross,first introduced by Mendel,is used to determine if an individual exhibiting a dominant trait is homozygous or heterozygous for that trait.
Test crosses involve breeding the individual in question with another individual that expresses a recessive version of the same trait.
If all offspring display the dominant phenotype,the individual in question is homozygous dominant.
If the offspring display both dominant and recessive phenotypes,then the individual is heterozygous.
$A$ test cross is a specific type of back cross where an individual is crossed with a recessive homozygote.

(A) The Assertion is correct because the genotype refers to the entire genetic makeup or the genetic complement of an organism.
The Reason is also correct because the genotype represents the hereditary information (alleles) that determines the traits of an organism.
Since the genotype is defined as the genetic complement,the Reason provides a valid explanation for why the term is used to describe the hereditary properties of an organism.
Therefore,both are correct and the Reason is the correct explanation of the Assertion.

(C) test cross is defined as the cross of an $F_1$ hybrid with its homozygous recessive parent to determine the genotype of the $F_1$ individual.
In a monohybrid test cross (e.g.,$Tt \times tt$),the offspring are produced in a $1:1$ ratio,where $50\%$ of the individuals exhibit the dominant trait and $50\%$ exhibit the recessive trait.
Therefore,the Assertion is correct because it accurately defines a test cross.
However,the Reason is incorrect because recessive individuals are indeed obtained in a monohybrid test cross.

(C) Punnett square is a graphical representation used to calculate the probability of all possible genotypes of offspring in a genetic cross.
It was developed by the British geneticist Reginald $C$. Punnett.
It helps in visualizing the production of gametes by the parents,the formation of zygotes,and the resulting genotypes of $F_1$ and $F_2$ generations.
Therefore,the correct option is $C$.

(N/A) Mendel selected pea plants to carry out his study on the inheritance of characters from parents to offspring.
He selected a pea plant because of the following features:
$1$. Peas have many visible contrasting characters such as $Tall/Dwarf$ plants,$Round/Wrinkled$ seeds,$Green/Yellow$ pods,$Purple/White$ flowers,etc.
$2$. Peas have bisexual flowers and therefore undergo self-pollination easily. Thus,pea plants produce offspring with the same traits generation after generation.
$3$. In pea plants,cross-pollination can be easily achieved by emasculation,in which the stamen of the flower is removed without affecting the pistil.
$4$. Pea plants have a short life span and produce many seeds in one generation.