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Genes and Chromosomes (Class - XII)

Description: proteins
Number of Questions: 30
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Tags: Chromosomes Chromosomal Theory of Inheritance
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Who proposed chromosomal theory of inheritance?

  1. Waldeyar

  2. Johannsen

  3. Sutton and Boveri

  4. Belling


Correct Option: C
Explanation:

Sutton and Boveri proposed chromosomal theory of inheritance in 1902.

What is the functional unit of a gene called?

  1. Muton

  2. Operon

  3. Cistron

  4. Recon


Correct Option: C
Explanation:

The functional unit of a gene is called cistron.

In which of the following is a nucleoid present?

  1. Bacteria

  2. Blue-green algae

  3. Both (1) and (2)

  4. Protists


Correct Option: C
Explanation:

Both bacteria and blue-green algae are prokaryotes and contain nucleoid.

How many chromosomes are there in a pigeon?

  1. 48

  2. 32

  3. 80

  4. 78


Correct Option: C
Explanation:

Pigeon has 80 chromosomes.

Which of the following plasmids is responsible for transfer of genetic material?

  1. Col-plasmid

  2. F-plasmid

  3. R-plasmid

  4. Expression plasmid


Correct Option: B
Explanation:

F-plasmid is responsible for transfer of genetic material.

What were the darkly stained bodies located inside the nucleus named by Waldeyar in 1888?

  1. Genes

  2. Chromosomes

  3. DNA

  4. Nucleotides


Correct Option: B
Explanation:

The darkly stained bodies located inside the nucleolus were named as chromosomes by Waldeyar in 1888. Chromosomes are called carriers of heredity. The chromosomes carry the genes and similarities of parents to the offsprings. Thus, these are called hereditary vehicles.

Which of the following organisms have the maximum number of chromosomes?

  1. Homo sapiens (man)

  2. Canis familiaris (dog)

  3. Aleucantha (radiolarian)

  4. Pattus rattus (rat)


Correct Option: C
Explanation:

Aleucantha (radiolarian) have 1600 chromosomes. Thus, it has the maximum number of chromosomes of all the given species.

Which of the following chromosomes is/are not present in a human cell?

a. Telocentric chromosome b. Holocentric chromosome c. Acrocentric chromosome

  1. Only a

  2. Only b

  3. Both a and b

  4. Only c


Correct Option: C
Explanation:

Human genomes do not have either telocentric or holocentric chromosomes.

A chromosome having unequal arms is called

  1. acrocentric

  2. metacentric

  3. sub-metacentric

  4. holocentric


Correct Option: C
Explanation:

If arms' lengths are unequal, the chromosome is said to be sub-metacentric.

Which is the best stage of mitotic cell division for studying chromosomes?

  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase


Correct Option: B
Explanation:

Metaphase is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their most condensed and coiled stage. Thus, it is the best stage for studying mitosis.

Which is the largest human chromosome?

  1. Chromosome 1

  2. Chromosome 7

  3. Chromosome 19

  4. Chromosome 15


Correct Option: A
Explanation:

The largest human chromosome is chromosome 1. Chromosome 1 spans about 249 million nucleotide base pairs.

The membrane bounding a chromosome is called

  1. chromosomal membrane

  2. pellicle

  3. tonoplast

  4. genetic coat


Correct Option: B
Explanation:

Each chromosome is bounded by a membrane called pellicle. It is very thin and is formed of achromatic substance.

A holocentric chromosome has

  1. only two centromeres

  2. chromosome without centromere

  3. a large number of centromeres scattered throughout the length of the chromosome

  4. only one centromere


Correct Option: C
Explanation:

A holocentric chromosome is where a large number of centromeres are scattered throughout the length of the chromosome.

Which of the following provide(s) stability to chromosomes?

  1. Centromeres

  2. Chromomeres

  3. Telomeres

  4. Secondary constriction


Correct Option: C
Explanation:

Telomeres provide stability to chromosomes. Telomeres are essential for protecting chromosome ends and ensuring chromosome stability.

Which of the following is a characteristic feature of metaphase?

  1. The chromosomes are single and condensed.

  2. The chromosomes are in the form of chromonema.

  3. A typical chromosome consists of two chromatids.

  4. Chromosomes bear bead-like structures called chromomeres.


Correct Option: C
Explanation:

A chromosome consists of two chromatids at metaphase.

The genes coding for 18S and 28S rRNA are present in

  1. nuclear membrane

  2. nucleolus

  3. nucleolar organiser region

  4. centromeres


Correct Option: C
Explanation:

A nucleolar organiser region contains genes for coding 18S and 28S ribosomal RNA.

What is the function of balbini rings of salivary gland chromosomes?

  1. Transcription of DNA

  2. Transcription of RNA

  3. Providing stability to chromosomes

  4. Acting as the origin of transcription


Correct Option: B
Explanation:

The balbini rings of salivary gland chromosomes function in transcription of RNA.

Which among the following characteristics is/are common between chromosomes 13, 14, 15, 21 and 22?

a. Being acrocentric b. Possessing nucleolar organiser c. Presence of same genes

  1. Only a

  2. Only b

  3. Only c

  4. Both a and b


Correct Option: D
Explanation:

Chromosomes 13, 14, 15, 21 and 22 are acrocentric and possess nucleolar organiser. Therefore, both (a) and (b) are correct.

TMV is a

  1. dsDNA virus

  2. ssDNA virus

  3. ssRNA virus

  4. dsRNA virus


Correct Option: B
Explanation:

TMV is a ssDNA virus.

Which of the following types of chromosomes help in the formation of certain amount of yolk material in eggs?

  1. Polytene chromosomes

  2. Lamp brush chromosomes

  3. Normal chromosomes

  4. Telocentric chromosomes


Correct Option: B
Explanation:

Lamp brush chromosomes help in the formation of certain amount of yolk material in eggs.

What do we call a small chromosomal segment separated from the main body of the chromosome by secondary constriction?

  1. Telomere

  2. Sub-telomeric centromere

  3. Satellite

  4. Acrocentric chromosome


Correct Option: C
Explanation:

A small chromosomal segment separated from the main body of the chromosome by secondary constriction is called satellite. In humans, it is usually associated with the short arm of an acrocentric chromosome.

Which of the following are the basic unit of DNA packaging in mature sperm cells?

  1. Nucleosomes

  2. Protamines

  3. Histones

  4. Peptones


Correct Option: B
Explanation:

Mature sperm cells largely use protamines to package their genomic DNA, most likely to achieve an even higher packaging ratio. Thus, these act as the basic unit of DNA packaging in mature sperm cells.

Which histone molecule is found with linker DNA?

  1. H2A

  2. H2B

  3. H1

  4. H3


Correct Option: C
Explanation:

H1 histone is found with linker DNA. It is involved in chromatin compaction and sit at the base of the nucleosome near the DNA entry and exit binding to the linker region of the DNA.

Which of the following parts of chromosomes never participate(s) in cross over?

  1. Centromere

  2. Telomere

  3. Chromatids

  4. Chromomeres


Correct Option: B
Explanation:

Telomeres never form permanent association with other parts of homologous or non-homologous chromosomes. Thus, they never participate in cross over.

Who proposed the nucleosome model for DNA packaging?

  1. Dupraw

  2. Roger Kornberg

  3. Aaron King

  4. Woodcock


Correct Option: B
Explanation:

Roger Kornberg proposed nucleosome model in 1975 for DNA packaging.

_____ are the prophase form of chromatids.

  1. Chromonemata

  2. Chromomeres

  3. Centromeres

  4. Balbini rings


Correct Option: A
Explanation:

The prophase form of chromatids are chromonemata.

What is the modern concept of a gene?

  1. It is a segment of DNA capable of crossing over.

  2. It is a functional unit of DNA.

  3. It is a segment of DNA.

  4. It is a segment of chromosome.


Correct Option: B
Explanation:

According to the modern concept, gene is a functional unit of DNA.

Which technique is used to quantify the length of a telomere?

  1. Giemsa technique

  2. Flow-FISH

  3. CREST-SERUM and Prpadium iodide

  4. Q-banding


Correct Option: B
Explanation:

Flow-FISH is most commonly used to quantify the length of telomeres, which are stretches of repetitious DNA (hexameric TTAGGG repeats) at the distal ends of chromosomes.

What are chromosomes composed of?

  1. Only DNA

  2. DNA and Proteins

  3. DNA, Proteins and RNA

  4. DNA and RNA


Correct Option: C
Explanation:

Chromosome is made up of DNA, histone protein and some chromosomal RNAs which may have a role in transcription.

The part of a chromosome where crossing over has taken place is called

  1. synapse

  2. centromere

  3. chiasmata

  4. secondary constriction


Correct Option: C
Explanation:

Chiasmata is the part of a chromosome where crossing over has taken place.

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