Definition of Nondisjunction

Q. Mendel's Law of independent assortment holds good for genes situated on the

1. homologous chromosomes
2. same chromosome
3. non-nuclear cytoplasmic chromosomes
4. non-homologous chromosomes

Q. Match column I with column II and choose the correct option.
$\begin{array}{cccc}& \text{Column l}& & \text{Column ll}\\ i.& \text{Monosomy}& a& 2n+1\\ ii.& \text{Tetrasomy}& b& 2n-1\\ iii.& \text{Tetraploidy}& c& 2n+2\\ iv.& \text{Trisomy}& d& 4n\end{array}$

1. i-b, ii-d, iii-c, iv-a
2. i-c, ii-b, iii-a, iv-d
3. i-d, ii-a, iii-c, iv-b
4. i-b, ii-c, iii-d, iv-a

Q. A daughter will not normally be colourblind, unless her mother is ___ and her father is ____.

1. carrier, colourblind
2. colourblind, normal
3. colourblind, carrier
4. carrier, carrier

Q.

What is the difference between pleiotropy and epistasis?

Q.

Is Down’s syndrome caused by an autosomal primary non-disjunction?

Q. During cell division, sometimes there will be failure of separation of sister chromatids. This event is called

1. interference
2. complementation
3. non-disjunction
4. coincidence

Q.

Crossing over occurs:

1. During pachytene

2. Between sister chromatids

3. During metaphase

4. During Anaphase-I

Q.

What is Downs syndrome?

Q. Select the incorrect matches with respect to the types of aneuploidy observed in human beings. $\begin{array}{ccc}& \text{Types of aneuploidy}& \text{Number of chromosomes}\\ i& \text{Nullisomy}& 44\\ ii& \text{Tetrasomy}& 48\\ iii& \text{Double Trisomy}& 47\\ iv& \text{Monosomy}& 46\end{array}$

1. i and ii
2. iii and iv
3. i and iii
4. ii and iv

Q.

Is translocation down syndrome inherited?

Q.

Can aneuploidy be cured?

Q.

How is down syndrome caused?

Q.

Given below are three statements (i - iii) each with one or two blanks. Select the option which correctly fills up the blanks in the below statements.

i. The condition in which multiples of the basic set is present in a cell is called ___A____.

ii. Aneuploidy caused due to removal of chromosomes is called as____B____ or addition of chromosomes is called as ____C___.

iii. If two additional chromosomes are present in a cell, then the type of hyperploidy is___D____.

Q. Men with Klinefelter syndrome do not show barr body because

1. They can inactivate extra copy of chromosome
2. They cannot activate the extra copy of chromosome
3. They have linked genes
4. All of the above

Q. Genetic recombination occurs due to

1. Mitosis and meiosis
2. Fertilisation and mitosis
3. Fertilisation and meiosis
4. None of the above

Q. A person who is monosomic for X-chromosome has

1. Down's syndrome
2. Patau's syndrome
3. Turner's syndrome
4. Edward's syndrome

Q. Out of the three copies of chromosome $21$ in a child, two have come from the mother. Based on this when did the nondisjunction event most likely occurred.

1. Maternal meiosis II
2. Paternal meiosis II
3. Maternal meiosis I
4. Paternal meiosis I

Q.

When an individual gets an extra chromosome from a parent the resulting condition is called ________.

1. Disjunction

2. Nondisjunction

3. Aneuploidy

4. Polyploidy

Q. Which of the following most accurately explains the cause for the abnormal number of chromosomes during human reproduction that can result in Down's syndrome, Turner's syndrome, or Klinefelter's syndrome?

1. The occurrence of non-disjunction of homologous chromosomes during meiosis
2. Duplicative production of extra chromosomes during DNA replication
3. The abnormal pairing of non-homologous chromosomes during meiosis I
4. The selective loss of particular chromosomes from sex cells after formation of the mature gamete

Q.

The failure of chromosomes to separate during cell division is known as:

1. aneuploidy

2. ploidy

3. nondisjunction

4. crossing over

Q. The failure of chromosomes to separate during cell division is known as .

1. aneuploidy
2. ploidy
3. non-disjunction
4. crossing over

Q. Failure of separation of sister chromatids is

1. Fusion
2. Nondisjunction
3. Complementation
4. Interference

Q. Two individuals produced from a single zygote are

1. Two girls looking similar
2. Two girls not looking similar
3. One boy and one girls not looking similar
4. Two boys not looking similar

Q. The failure of chromosomes to separate during cell division is known as .

1. aneuploidy
2. ploidy
3. non-disjunction
4. crossing over

Q. The failure of chromosomes to separate during cell division is known as .

1. aneuploidy
2. ploidy
3. non-disjunction
4. crossing over

Q.

When an individual gets an extra chromosome from a parent the resulting condition is called ________.

1. Polyploidy

2. Disjunction

3. Nondisjunction

4. Aneuploidy

Q.

The failure of chromosomes to separate during cell division is known as:

1. Aneuploidy

2. Ploidy

3. Non-disjunction

4. Crossing over

Q.

The failure of chromosomes to separate during cell division is known as:

1. Aneuploidy

2. Ploidy

3. Non-disjunction

4. Crossing over

Q. State the following statements are true or false.
The process of meiosis guarantees the presence of complete sets of either the maternal or paternal chromosomes in animal gametes.

1. True
2. False