Tag: biology

Questions Related to biology

The sex chromosomes of .......... determine the sex of an unborn baby.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Male

  2. Female

  3. Grand parent

  4. None of the above

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Correct Option: A
Explanation:
The sex of a human baby is determined by the composition of its sex chromosomes (a single distinct pair among humans 23 pairs of chromosomes). Females possess two copies of the same chromosome (referred to as the 'X' chromosome); males have one copy of the X chromosome and one copy of the smaller, hook-shaped Y chromosome.
When fertilization occurs, the new gamete (the initial cell from which a fetus grows) always inherits one of the mother's X chromosomes, and either a X or a Y from the father, depending on which chromosome the fertilizing sperm cell happened to inherit. One could say, then, that the father—or, at least, his sperm—determines the sex of the child. 

The given statement is true or false. Sex of baby mainly depends on male.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. When X chromosome containing sperm fuses with ovum, male foetus develops.

  2. When Y chromosome containing sperm fuses with ovum, male foetus develops.

  3. When X chromosome containing sperm fuses with ovum, female foetus develops.

  4. Both B and C

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Correct Option: D
Explanation:

The chromosome in the human female is XX while that in the male is XY.
If a sperm carrying X chromosome fertilizes an ovum or egg, which carries X chromosome, then the child born will be a girl (female). This is because the child will have XX combination of sex chromosomes.
If a sperm carrying Y chromosome fertilizes an ovum, which carries X chromosome, then the child will have XY combination of sex chromosome and hence it will be a male child.
Thus, the correct answer is the option (D), 'Both B and C.'.

A zygote which has inherited a Y chromosome from the father will develop into

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. A boy

  2. A girl

  3. Anyone of the above

  4. None of the above

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Correct Option: A
Explanation:

XY type of sex determination is seen in humans. Genetic makeup of female is XX and that of male is XY. A female ovum always carries a X chromosome and male sperm can carry either X or Y chromosome.

The human which has an XX pair of chromosomes is called 

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Male

  2. Female

  3. Hybrid

  4. Pure breed

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Correct Option: B
Explanation:

Humans have X and Y sex chromosomes. A human with 22 pairs of autosomes and two copies of X chromosomes as sex chromosomes are females while those with 22 pairs of autosomes and XY chromosomes as sex chromosomes are males. A pure breed refers to individual that have a pair of identical alleles for a particular locus while a hybrid carries unlike alleles for a particular locus. The correct answer is B.

If a couple has three daughters, what are the chances that the fourth child will be a son?

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. 100%

  2. 75%

  3. 50%

  4. 0%

Show answer
Correct Option: C
Explanation:

Each pregnancy has a 50% chance of resulting in a boy or girl and this does not include the possibility of multiples. Having 3 daughters previously does not affect the chances of any resulting pregnancy. The chance of having a boy remains at 50%. Thus, the correct answer is option C. 

In humans, an egg involved in male child formation has the genetic constitution of 

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. 22 + X

  2. 22 + Y

  3. 44 + XY

  4. 44 + XX

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Correct Option: A
Explanation:

Human follows XX- XY mechanism of sex determination. Human females have 46 chromosomes arranged in 22 homologous and homomorphic autosomes and two copies of X chromosomes as sex chromosomes (44+XX). Males have 22 homomorphic pairs and one heteromorphic pair, the XY pair (44+XY). During meiosis, all the gametes produced by females contain only the X chromosome (22 + X), whereas males produce two kinds of gametes, 1/2 gametes with X- and 1/2 with Y-chromosome (22 + X and 22 + Y). Fertilization of egg (22 + X) with sperm carrying 22+X chromosomes results in female child (44 + XX). Fertilization of egg (22 + X) with the sperm carrying 22+Y chromosomes results in a male child (44A + XY) as the zygote is a diploid structure and consists of two complete sets of chromosomes. Thus, the correct answer is option A.

A zygote which has an X chromosome inherited from the father will become

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Boy

  2. Girl

  3. Either girl or boy

  4. Cannot be predicted

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Correct Option: B
Explanation:

Sex determination seen in humans is XY sex determination. Ovum carries X chromosome, whereas sperm can carry either X or Y chromosome. The genetic makeup of a female is XX and genetic makeup of male is XY. Therefore, if the zygote is formed by receiving the X chromosome from the father, the resulting zygote will be a female. 

The karyotype of a normal male is

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. 22 AA + XY

  2. 44 AA + XY

  3. 22 A + XY

  4. Both A and B

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Correct Option: B
Explanation:

The karyotype of a normal human contains 22 pairs of autosomal chromosome and one pair of sex chromosome called as allosomes. Female contains 2 X chromosomes and 46 autosomes and male contains 1 X and 1 Y chromosome and 46 autosomes.

When a sperm containing Y chromosome fertilizes an egg with X chromosome, the zygote develops into a .......... child.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Female

  2. Either a male or female

  3. Male

  4. No child

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Correct Option: C
Explanation:

In human, the genetic makeup of female is XX and that of male is XY. Female ovum carries X chromosome, whereas the male sperm may carry either X chromosome or a Y chromosome. Therefore, if the sperm is carrying Y chromosome fertilizes an egg with X chromosome, the zygote develops into a male child.

The sex chromosomes of both male and female are respectively

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. YY, XX

  2. YX, XY

  3. XY, XX

  4. All of the above

Show answer
Correct Option: C
Explanation:

Humans have 22 pairs of chromosome of which one pair of sex chromosome is not always a perfect pair. Women have a perfect pair of X chromosome but, men have a mismatched pair of X and Y chromosome. Therefore, (c) is the correct answer.