M.C.Q

MCQ 1511 Mark

Structure present in a cell which is responsible for determination of the sex of a baby is :

A
Cytoplasm
B
Cell membrane
C
Nucleus
✓
Chromosome

Answer

Correct option: D.

Chromosome

Human cells are having two types of chromosomes: autosomes and sex chromosomes.
Sex chromosomes in a male are $XY$ and in females they are $XX$.There are no differences in the cytoplasm or membrane.
The chromosome is present inside a nucleus.

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MCQ 1521 Mark

A pure tall and a pure dwarf plant were crossed to produce offsprings.If offsprings were self crossed, then the ratio between true breeding tall to true breeding dwarf would be :

✓
$1 : 1$
B
$3 : 1$
C
$2 : 1$
D
$1 : 2 : 1$

Answer

Correct option: A.

$1 : 1$

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MCQ 1531 Mark

Which one of the following pairs of vegetables is an example of homologous structures :

A
Potato and sweet potato.
✓
Carrot and radish.
C
Carrot and tomato.
D
Tomato and radish.

Answer

Correct option: B.

Carrot and radish.

Homologus organs are defined as the organs which have same structure but different functions. Radish and carrot are a pair of homologus organs as they are modified roots.

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MCQ 1541 Mark

The two versions of a trait $($character$)$ which are brought in by the male and female gametes are situated on :

A
Copies of the same chromosome.
✓
Two different chromosomes.
C
Sex chromosomes.
D
Any chromosome.

Answer

Correct option: B.

Two different chromosomes.

This is the reason; one version is expressed in some progenies, while another version is expressed in some other progenies.

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MCQ 1551 Mark

A recessive homozygote is crossed with a heterozygote of the same gene. What will be the phenotype of the $\mathrm{F}_1-$ generation?

A
$25\%$ dominant, $50\%$ heterozygous, $25\%$ recessive.
B
$75\%$ dominant, $25\%$ recessive.
✓
$50\%$ dominant, $50\%$ recessive.
D
All dominant.

Answer

Correct option: C.

$50\%$ dominant, $50\%$ recessive.

Let us take $tt$ as homozygous recessive $Tt$ as heterozygous dominant. So the cross will be $Tt \times tt.$
the progenies in $\mathrm{F}_1$ generation are :

$Tt$	$tt$
$Tt$	$tt$

So $Tt\ ($dominant phenotype$) : tt\ ($recessive phenotype$) = 1 : 1$
therefore, $50\%$ dominant $50\%$ recessive.

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MCQ 1561 Mark

Which of the following pairs of two vegetables represents the correct homologous structures?

A
Sweet potato and potato.
B
Sweet potato and tomato.
C
Carrot and potato.
✓
Radish and carrot.

Answer

Correct option: D.

Radish and carrot.

Homologus organs are defined as the organs which have same structure but different functions. Radish and carrot are a pair of homologus organs as they are modified roots.

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MCQ 1571 Mark

Which statement is true for a dominant allele?

A
It cannot undergo mutation.
B
It gives a greater chance of survival than a recessive allele.
✓
It gives the same phenotype in heterozygotes and homozygotes.
D
It is only responsible for male characteristics.

Answer

Correct option: C.

It gives the same phenotype in heterozygotes and homozygotes.

Allele which can express themselves in heterozygous conditions are dominant alleles while which does not are recessive allele.
Thus dominant allele gives the same phenotype in heterozygote and homozygote.
E.g. $TT$ has a phenotype of tall height $Tt$ also has a phenotype of tall height.

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MCQ 1581 Mark

Select the group which shares the maximum number of common characters :

✓
Two individuals of a species.
B
Two species of a genus.
C
Two genera of a family.
D
Two genera of two families.

Answer

Correct option: A.

Two individuals of a species.

Two individuals of a species share the maximum number of common characters.

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Science M.C.Q