Biology

Cell Cycle and Chromosomes

1,219 Questions

Explore a curated list of questions covering the cell cycle, mitosis, and meiosis. Topics include DNA replication, chromosomal structures, and genetic disorders. This material is essential for students preparing for biology and general science competitive exams.

Cell cycle eventsDNA replicationMeiosis processChromosomal structuresGenetic disorders

Cell Cycle and Chromosomes Questions

Multiple choice zoology health and diseases diabetes mellitus lifestyle diseases non-infectious diseases

Which is most common chromosomal aberration seen in cancer-

  1. Deletion

  2. Invention

  3. Duplication

  4. Translocation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A deletion mutation occurs when part of a DNA molecule is not copied during DNA replication. This uncopied part can be as small as single nucleotide or as much as an entire chromosome. The loss of this DNA during replication can lead to genetic disease.

So, the correct option is 'Deletion'.

Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

Which of the following is unique in every human being?

  1. Satellite DNA

  2. NOR

  3. Microsatellite DNA

  4. Mini-micro-satellite DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A mini-micro-satellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from 10–60 base pairs) are typically repeated 5-50 times. Minisatellites occur at more than 1,000 locations in the human genome and they are notable for their high mutation rate and high diversity in the population.
So, the correct answer is 'Mini-micro-satellite.'
Multiple choice zoology mutation dna fingerprinting human genome project and dna fingerprinting instruments in biotechnology

Which is different in related species?

  1. Position of centromeres

  2. Position of NOR

  3. Satellite DNA

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

Satellite DNA consists of arrays of tandemly repeating sequences that are widely present (>30%) in the genome. Satellite DNA is mainly present in heterochromatin or the tightly packed regions of chromosomes in centromeres, telomeres, and sometimes even in the euchromatin region (active region of the genome).

So, the correct answer is 'Satellite DNA.'

Multiple choice botany modes of reproduction why do plants reproduce? reproduction and variation the life cycle of plants

Which statement describes human cells formed by meiosis?

  1. They are genetically identical and they become gametes.

  2. They are genetically identical and they become tissues.

  3. They are not genetically identical and they become gametes.

  4. They are not genetically identical and they become tissues.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In women, both sex chromosomes are the same and are therefore called as XX. In males, they are different and called as XY. When sperm and eggs (ova) are made during meiosis they separate to form different gametes. As women have XX, their eggs always carry the X chromosomes. As males have XY, approximately half their sperm carry the X chromosome while the remainder carries the Y chromosome.

Multiple choice biology butterfly and honey bee life cycle of a butterfly metamorphosis in frogs the life of a butterfly types of reproduction in animals oviparous and viviparous

If the sperm and egg cells of a butterfly have six chromosomes, how many chromosomes will be there in the maggot larvae?

  1. $6$
  2. $18$
  3. $12$
  4. $3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If the sperm and egg cells of a butterfly have six chromosomes, 12 chromosomes will be there in the maggot larvae. This is because maggot larvae forms due to the fusion of egg and sperm cells. Since egg contains 6 and sperm cells contains 6 chromosomes, maggot larvae will get both sperm cell and egg cell chromosomes. Thus, the correct answer is option C.

Multiple choice botany plant biology introduction to angiosperms phanerogams angiosperms

Endosperm cell of an angiosperm has $24$ chromosomes. The number of chromosomes in the gametes would be.

  1. $8$
  2. $16$
  3. $24$
  4. $48$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The endosperm in angiosperms is triploid (3n). If 3n = 24, then n = 8. Gametes are haploid (n), so they contain 8 chromosomes.

Multiple choice botany plant biology introduction to angiosperms phanerogams angiosperms

In an angiosperm, a female plant having $2n=24$ is crossed with a male plant having $2n=12$. What will be the chromosome number of endosperm.

  1. $12$
  2. $18$
  3. $24$
  4. $30$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Endosperm is formed by the fusion of one male gamete (n) and two polar nuclei (n+n). The female plant is 2n=24, so n=12. The male plant is 2n=12, so n=6. Endosperm = (n from male) + (n from female) + (n from female) = 6 + 12 + 12 = 30.

Multiple choice zoology locomotion and reproduction flagella other cell components single membrane bound organelles

Arrangement of microtubules in a flagellum and a centriole is _______ and ________ respectively.

  1. $9 + 2$ and $9 + 1$
  2. $9 + 1$ and $9 + 0$
  3. $9 + 0$ and $9 + 2$
  4. $9 + 2$ and $9 + 0$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A centriole possesses a whorl of nine peripheral fibrils. Fibrils are absent in the centre. The arrangement is, therefore, called $9 + 0$. Flagellum contains an axoneme of a peripheral doublet fibrils and $2$ central singlet fibrils. This arrangement is called $9 + 2$ or $11$ stranded.
So, the correct answer is '9+2 and 9+0'.
Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Choose the correct answer from the alternatives given :
Which of the following statements regarding human genome is incorrect?

  1. Human genome consists of $3 \, \times \, 10^9$ bp and about 20,500 genes.

  2. The average gene size is 3000 bop and dystrophin is the largest known human gene.

  3. Chromosome 1 contains maximum (2968) number of genes and Y-chrbmosome has the least (231) number of genes.

  4. Repeated (or repetitive) sequences are not present in human genome.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Repeated or repetitive sequences make up large portion of human genome. Repetitive sequences are nucleotide sequences that are repeated many times, sometimes hundred to thousand times. They have no direct coding function but provide information as to chromosome structure, dynamics and evolution. Approximately 1 million copies of short 5-8 base pair repeated sequences are clustered around centromeres and near the ends of chromosomes. They represent junk DNA. 

So, the correct answer is 'Repeated (or repetitive) sequences are not present in human genome'.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Number of genes believed to be present in a human being is

  1. 1000

  2. 10,000

  3. 100,000

  4. 1,000,000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The human genome consists of 50,000 to 100,000 genes located on 23 pairs of chromosomes. One chromosome in each pair is inherited from the mother, the other from the father. Each chromosome contains a long molecule of DNA, the chemical of which genes are made. 

So, the correct answer is '100,000.'

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Number of genes present in human genome is about

  1. 15,000

  2. 21,000

  3. 27,000

  4. 30,000
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A gene is a distinct sequence of nucleotides forming part of a chromosome.
Most of the genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. The Human Genome Project estimated that humans have around 21,000 genes.
So, the correct option is '21,000'.
Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

Choose the wrong statement regarding the observation drawn from Human Genome Project

  1. Repetitive sequences are stretches of RNA

  2. Less than 2% of the genome codes for protein

  3. Chromosome Y has the fewest number of genes

  4. SNPs help in tracing human history

  5. Repetive sequences make up a very large portion of the human genome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Repetitive sequences are stretches of DNA, not RNA. The other statements regarding the small percentage of protein-coding genes, the low gene count on the Y chromosome, and the utility of SNPs are correct findings from the HGP.

Multiple choice zoology molecular basis of inheritance genome projects human genome project human genome project and dna fingerprinting

All of the following except are sources of change in the genome

  1. Nondisjunction during meiosis

  2. Gene mutations

  3. Crossing over

  4. Amniocentesis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A process in which amniotic fluid is sampled using a hollow needle inserted into the uterus, to screen for abnormalities in the developing fetus.

It is not part of the change in a genome, so the correct answer is D, amniocentesis.