Biology

Cell Cycle and Chromosomes

1,348 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 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.

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

The human genome project involves all of the following except

  1. altering the human genome

  2. physical mapping of the chromosomes

  3. sequencing of the entire nucleotide sequence of the human genome

  4. location of RFLP markers
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The Human Genome Project (HGP) was launched on 1st October 1990 for sequencing the entire genome of 2.75 billion nucleotide pairs. This megaproject was a 13-year project coordinated by the U.S. Department of Energy and the National Institute of Health. During the early years of the HGP, the Wellcome Trust (U.K.) becomes a major partner; additional contributions come from Japan, France, Germany, China, and others. The project was completed in 2003. This project had the following objectives:-
  • To identify all the approximately 20,000-25,000 genes in human DNA.
  • To determine the sequences of the 3 billion base pairs that make up human DNA. 
  • Knowing locations of RFLP markers. Restriction fragment length polymorphism (RFLP) is a technique that exploits variations in homologous DNA sequences. The principle of RFLP markers is that any genomic DNA can be differentiated according to the presence or absence of restriction enzyme sites. 
  • Mapping presence of genes on different chromosomes. 
So, the correct option is 'altering the human genome'.
Multiple choice biology seeds - structure and germination germination seed germination the flower

How many chromosomes are present in each of the following with respect to maize plants respectively?
I. Leaf epidermal cell II. Antipodal cell III. Endosperm cell
IV. Generative cell V. Egg cell VI. Megaspore

  1. $10, 20, 10, 10, 10, 20, 30$
  2. $20, 10, 30, 10, 10, 10, 20$
  3. $20, 10, 10, 10, 20, 30, 10$
  4. $30, 10, 20, 10, 20, 10, 10$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice zoology the paths traversed by life mutational theory of evolution theories of evolution other theories of evolution

De Vires' Oenothera lamarckiana was 

  1. Complex heterozygote with anomalous chromosome behaviour

  2. Homozygous with fragile chromosome

  3. Heterozygote which developed gene mutations

  4. Homozygous with stable chrmosomes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hugo De Vries gave Mutation theory in 1901. He worked on plant Oenothera lamarckiana, commonly known as evening primrose and found several aberrant types. When the plant was self-pollinated and its seeds were allowed to grow, the majority of F$ _1$ plants were similar to the parents, but a few were different plants. Same results were found in F$ _2$ generation. He resulted in that origin of species is through sudden, large changes of traits from another species and these sudden changes are due to Mutation in the gene pool which passes from one generation to another. Later on, it was revealed that most of the variants isolated from Oenothera lamarckiana were due its anomalous chromosome behaviour i.e., chromosome forms multiple rings at meiosis and chromosomal end segments only involves in recombination (low-level crossing over) and plant shows complex heterozygosity i.e., during meiosis maternal and paternal chromosomes are arranged in alternate order. Thus, the correct answer is ‘Complex heterozygote with anomalous chromosome behaviour.’

Multiple choice female reproductive structure reproductive system of human hormones, homeostasis, and reproduction human physiology biology

An unfertilized human egg would have

  1. Two X - chromosome

  2. One X - chromosome

  3. One Y - chromosome

  4. Both X and Y - chromosome
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The gametes are the haploid cells which are produced by the meiotic division. The egg is the female gamete which is produced through oogenesis. The gametes are haploid and contain only one set of the chromosome. So, the egg cell contains the 22 autosomes and one X chromosome. Since the female somatic cell contains two X chromosome, there will be only one X chromosome in the gamete.

Thus, the correct answer is option B. 

Multiple choice female reproductive structure reproductive system of human hormones, homeostasis, and reproduction human physiology biology

The ratio of the number of chromosomes in a human zygote and a human ovum (egg) is

  1. 1 : 2

  2. 1 : 4

  3. 2 : 1

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

The reproductive cells contain only half the number of chromosomes as compared to the normal body cells of an organism. The human sperm and egg have 23 chromosomes each. So when they fuse together, the zygote formed has 23+23=46 chromosomes. So the required ratio is 46 : 23, i.e., 2 : 1.

Multiple choice dna replication replication and protein synthesis nucleic acids and protein synthesis heredity biology

DNA replication takes place at ________ phase of the cell cycle

  1. G$ _1$

  2. S
  3. G$ _2$

  4. M
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In eukaryotes, the replication of DNA takes place at S-phase of the cell cycle. The replication of DNA and cell division cycle should be coordinated. A failure in cell division after DNA replication results into chromosomal anomaly.

Multiple choice zoology immune system active and passive immunity immunity related disorders and problems diseases and immunity

Major histocompatibility (MHC) complex genes are present in which of the following chromosome of humans?

  1. Chromosome 22

  2. Chromosome 7

  3. Chromosome 6

  4. X chromosome
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances Major histocompatibility (MHC) complex genes. In vertebrates, the major histocompatibility complex (MHC) genes present on chromosome 6 code for a set of cell surface proteins that are  essential for the acquired immune system to recognize foreign molecules, which determines histocompatibility.

So, the correct  option is 'chromosome 6'.
Multiple choice bio-chemistry cell biology cytoplasm the components in a cell component of the cell

In rotation type of cyclosis, the cytoplasmic matrix flows in _____________.

  1. One direction

  2. Two opposite directions

  3. Different directions

  4. Side-ways
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Answer is "One direction" i.e. option A
Cyclosis are movements of cytoplasm within a cell. Cylosis is said to be rotational when the protoplasm moves around a single central vacuoles in either clockwise or anticlockwise direction. Such movement of cytoplasm are observed in leaf cells of Hydrilla, Vallisneria.
Multiple choice bio-chemistry cell biology cytoplasm the components in a cell component of the cell

The process of growth and division takes place in the

  1. Nucleus

  2. Plasma

  3. Cytoplasm

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

Cytoplasm is the jelly-like fluid present in cells that hold organelles and surrounded by the cell membrane. The processes of growth, expansion, as well as the division of the cell, take place in the cytoplasm. The nutrients are absorbed and stored in the cytoplasm so that these can be used by various organelles when needed. The cytoplasm also helps to dissolve the waste products.