Tag: biology

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

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

  1. Male

  2. Female

  3. Grand parent

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 
Multiple choice biology mendel's law of inheritance determination of sex sex determination sex determination in humans

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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.'.

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

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

  1. A boy

  2. A girl

  3. Anyone of the above

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

The human which has an XX pair of chromosomes is called 

  1. Male

  2. Female

  3. Hybrid

  4. Pure breed
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. 100%

  2. 75%

  3. 50%

  4. 0%
Reveal answer Fill a bubble to check yourself
C Correct answer
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. 

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

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

  1. 22 + X

  2. 22 + Y

  3. 44 + XY

  4. 44 + XX
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. Boy

  2. Girl

  3. Either girl or boy

  4. Cannot be predicted
Reveal answer Fill a bubble to check yourself
B Correct answer
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. 

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

The karyotype of a normal male is

  1. 22 AA + XY

  2. 44 AA + XY

  3. 22 A + XY

  4. Both A and B
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. Female

  2. Either a male or female

  3. Male

  4. No child
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

The sex chromosomes of both male and female are respectively

  1. YY, XX

  2. YX, XY

  3. XY, XX

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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.