Chromosomes

Q.

How many such beads (nucleosomes) do you imagine are present in a mammalian cell?

Q. A pink flowered snapdragon plant is crossed with white flowered snapdragon plant. What would be the ratio of red, pink and white flowered plants in F${}_1$ generation?
[0.7 mark]

1. Red : Pink = 2 : 1
2. Pink : White = 1 : 1
3. Red : White = 1 : 1
4. Red : Pink : White = 1 : 2 : 1

Q. Recombinant DNA technology involves several steps in specific sequence. Find out the correct sequence.

a. Fragmentation of DNA
b. Culturing the host cells in a medium at large scale
c. Ligation of DNA fragment into a vector
d. Extraction of the desired product
e. Isolation of DNA
f. Isolation of desired DNA fragment
g. Transferring the recombinant DNA into the host

1. e–a–f–g–c–b–d
2. e–f–a–c–g–b–d
3. a–e–c–f–g–d–b
4. e–a–f–c–g–b–d

Q. The expression of z, y, a genes in lac operon is controlled by

1. regulator
2. operator
3. promoter
4. structural

Q.

In which part of interphase do the replication of cell organelles take place (G1 or G2)??

Q. Can you think for how long the lac operon would be expressed in the presence of lactose?

Q. If the gene encoding the lac repressor is mutated so that it can no longer bind the operator, will transcription of that operon occur?

1. Yes, because the operator will not be bound by repressor and RNA polymerase can transcribe the lac operon
2. No, because RNA polymerase is need to transcribe the genes
3. Yes, but only when lactose is present
4. No, because cAMP levels are low when the repressor is nonfunctional
   

Q. The structural genes of lac operon transcribe mRNA which is

1. polycistronic
2. replicative
3. monocistronic
4. monokaryotic

Q. Replication of full-length chromosome of fast growing E.coli takes

1. lesser time than it takes E.coli to divide
2. variable time depending on the nitrogen source of the medium
3. longer time than it takes E.coli to divide
4. exactly as long as it takes E.coli to divide

Q.

Heterozygous purple flower is crossed with recessive white flower. The progeny has the ratio:

1. 50% purple and 50% white

2. 75% purple and 25% white

3. All white

4. All purple

Q.

Chromosome theory of inheritance was proposed by

1. Sutton and Boveri

2. Morgan and Mendel

3. Hershey and Chase

4. Watson and Crick

Q.

__ united the knowledge of chromosomal segregation with Mendelian principles.

Q.

Differences between acrocentric and telocentric chromosome

Q. Separation of daughter chromosomes occurs during

1. cytokinesis
2. karyokinesis
3. S phase
4. $G_2$ phase

Q.

A cross between two snapdragon varieties- one with red flowers and one with white flowers produces $F_1$ hybrids all with pink flowers .This is an example for

1. codominance

2. complete dominance

3. incomplete dominance

4. Multiple allelism

Q.

Question 13
Name a stain commonly used to colour chromosomes.

Q. The female gamete (ovum) has________.

1. one Y chromosome
2. two X chromosomes
3. one X chromosome
4. both X and Y chromosomes

Q. If the sex-determining ratio given by X chromosome by autosome(X/A) is 0.5 in Drosophila, then sex will be:

1. Male
2. Female
3. Superfemale
4. Intersex

Q.

Question 4

Which of the following stain is not used for staining chromosomes?

(a) Basic fuschsin (b) Safranin

(c) Methylene blue (d) Carmine

Q. The recombination frequency between the genes a & c is 5%, b & c is 15%, b & d is 9%, a & b is 20%, c & d is 24 and a & d is 29%. What will be the sequence of these genes on a linear chromosome?

Q. What is not true for DNA in prokaryotes?

1. present in the form of a compact structure called nucleoid
2. the coils are maintained by non-histone basic proteins
3. found in cytoplasm in a supercoiled condition
4. packaged as nucleosomes along with histones

Q.

Difference between male heterogamety and female heterogamety

Q. Chromosome is a condensed form of DNA. A skin cell of a human female will have _____.

1. 22 autosomes and 1 allosome
2. 22 pairs of autosomes and 1 pair of allosome
3. 22 allosomes and 1 autosome
4. 22 pairs of allosomes and 1 pair of autosome

Q.

The term genome denotes

1. Bivalent

2. Diploid chromosomal set

3. Haploid set of chromosomes

4. Monovalent

Q. The ___ (a) ____ structure in chromatin is packed to form chromatin fibers that are further coiled and condensed at _____ (b)___ stage of cell division to form chromosomes. Here, a and b are

1. chromosome, late prophase
2. beads-on-string, metaphase
3. nucleosome, late metaphase
4. chromonemata, mid prophase

Q. Root cell of wheat has 42 chromosomes. What would be the number of chromosomes in the synergid cell?

1. 14
2. 21
3. 28
4. 7

Q.

Define the term cell. Also, define the types of cells.

Q. Plants are more readily manipulated by genetic engineering than animals because

1. recombinant genes can be inserted into plant cells by microinjection
   
2. a somatic plant cell can grow into a complete plant
   
3. more vectors are available for transferring recombinant DNA into plant cells
4. plant genes do not contain introns
   

Q. If the number of bivalents are 8 in metaphase-I, what shall be the number of chromosomes in daughter cells after meiosis -1 and meiosis - II respectively?

1. 8 and 4
2. 4 and 4
3. 8 and 8
4. 16 and 8

Q. What is the importance of genetic code in protein biosynthesis? [2 marks]