(a) Identify the phase (b) What is the diploid number of chromosomes shown in them? (c) Identify whether A, B & C are animal cells or plant cell? Answers: (a) Metaphase (b) Four (c) A- Animal...
Shown below are four stages (A, B, C, D) (not in sequence) of a certain kind of cell division.
1. Is it a plant cell or an animal cell? Give two reasons 2. Is it undergoing mitosis or meiosis? 3. What should be the correct sequence of these four stages among themselves? 4. Name the stage that...
Given below is a diagram representing a stage during mitotic cell division. Study it carefully and answer the questions that follow:
(a) Is it a plant cell or an animal cell? Give a reason to support your answer. (b) Identify the stage shown. (c) Name the stage that follows the one shown here. How is that stage identified? (d)...
Given below is a diagram representing a stage during mitotic cell division in an animal cell. Examine it carefully and answer the questions which follow.
(a) Identify the stage. Give one reason in support of your answer. (b) Name the cell organelle that forms the ‘aster’. (c) Name the parts labelled 1, 2 and 3. (d) Name the stage that follows the one...
The diagram given below represents a certain phenomenon which occurs during meiosis. Name and explain the phenomenon by using the terms – homologous chromosomes, chromatids, and crossing-over.
The exchange of chromatids between homologous ones is known as Crossing-over. 1. Chromosome number is divided in half of the gametes so that during the fertilization, the normal number (2n) is...
Draw a labelled diagram to show the metaphase stage of mitosis in an animal cell having ‘6’ chromosomes.
The diagram below represents a stage during cell division. Study the same and then answer the questions that follow:
a. Name the parts labelled 1, 2 and 3. b. Identify the above stage and give a reason to support your answer. c. Mention where in the body this type of cell division occurs. d. Name the stage prior...
The three sketches given below (A, B and C) are intended to represent the replication of DNA. What should be their correct sequence starting with the first and ending with the last?
Answer:
Given below is a schematic diagram of a portion of DNA.
(a) How many strands are shown in the diagram? (b) How many nucleotides have been shown in each strand? (c) Name the parts numbered 1,2,3,4 and 5 respectively. (d) Name the DNA unit constituted by...
Why is meiosis referred to as ‘reductional division’?
Meiosis is a type of cell division that produces sex cells or gametes. It occurs in the reproductive organs (testis and ovary) in humans to produce sperm and ova. In flowering plants, it occurs in...
Name and explain the various stages of the cell cycle.
A cell cycle is a series of events that take place in a cell that leads to the replication of its DNA and subsequent division of the cell to produce two daughter cells. The cell cycle consists of...
Enumerate the various changes that occur in the nucleus of the cell during (a) prophase (b) anaphase of mitotic division.
Prophase: Centrioles began to separate and reached the opposite poles. 2. Chromosomes vary. 3. Chromosomes are already duplicated as paired chromatids. 4. The chromatids are attached to a small...
What are genes?
Genes are the direct sequence of nucleotides in the chromosome, which include specific proteins that express the state of a particular body part. It is the genes that are passed on from one...
What are chromosomes?
When an unrestricted living cell is seen under a bright microscope, its nucleus may appear to contain nothing inside. But when the same cell has the right spots, several structures are visible in...
Mention whether the following statements are true (T) or false (F). Give reason in support of your answer.
(a) As you grow from childhood to adulthood, your skin cells divide only to replace such cells that are lost from the surface. (b) The unfertilized human egg has half the number of chromosomes of...
“Gametes must be produced by meiosis for sexual reproduction”. Why is it so?
When male and female gametes merge during fertilization, a normal number of double chromosomes are rediscovered. This is why gametes should be produced by meiosis for sexual reproduction.
“First meiotic division is the reduction division”. What does the word ‘reduction’ refer to in this statement?
Reduction is the number of chromosomes in the sex cells divided in half such as 23 pairs of chromosomes in humans, only chromosomes are the number one pairs of cells that are passed on to the sex...
State the difference between:
(a) Chromosome and chromatid (b) Centrosome and Centromere (c) Aster and spindle fibres (d) Haploid and diploid (a) Chromosome and chromatid ChromosomeChromatinChromosomes are nucleus that contains...
Correct the following statements if there is any mistake.
1. The four nitrogenous bases in the DNA are Guanine, Thiamine, Adrenaline and Cytosine. 2. Genes are specific sequences of bases on a chromosome. 3. A nucleotide is composed of a sulphate, a sugar...
What are the rungs of the “DNA ladder” made of?
The rungs of the “DNA ladder” is made up of, Adenine (A) 2. Guanine (G) 3. Cytosine (C) 4. Thymine (T).
What is the difference between chromatin fibre and chromosome?
ChromosomeChromatinChromosomes are nucleus that contains cell’s DNA which is arranged into discrete units.Chromatin is a chromosome that contains one single long DNA molecule connected with many...
4. Fill in the blanks
1. DNA replicates in the …………. of the cell cycle. 2. Mitosis occurs in our …………. cells. 3. Mitosis produces two daughter cells, whereas meiosis produces ………… daughter cells. 4. Meiosis occurs only...
Match the events given in column A with the phase in mitotic cell division in column B
COLUMN ACOLUMN BChromosomes become arranged in a horizontal plane at the equatorAnaphaseDaughter chromosomes move to the opposite poles of a spindleProphaseChromosomes become visible as fine long...
Imagine one cell (A) has undergone one mitotic division and another cell (B) has completed its meiotic division. How many cells would the two produce?
Cell A produces 2 cells Cell B produces 4 cells
Name the following:
1. The repeating components of each DNA strand lengthwise. 2. The complex structure consisting of DNA strand and a core of histones. 3. The type of bond which joins the complementary nitrogenous...
Synthesis phase in the cell cycle is called so for the synthesis of more of
(a) RNA (b) RNA and proteins (c) DNA (d) Glucose Answer: (c) DNA
In which one of the following options the stages of mitosis have been given in correct sequence?
(a) Prophase, metaphase, telophase, anaphase (b) Prophase, metaphase, anaphase, telophase (c) Anaphase, telophase, prophase, metaphase (d) Telophase, anaphase, prophase, metaphase Answer: (b)...
3. The number of chromosomes in a certain type of cell division is halved. This kind of cell division occurs in
(a) only testis (b) only ovary (c) both ovary and testis (d) all body cells Answer: (c) both ovary and testis
The term “chromosomes” literally means
(a) Inherited bodies (b) Twisted threads (c) Colored bodies (d) Shining threads Answers: (c) Colored bodies
The chromatin material is formed of
(a) DNA only (b) DNA and Histones (c) Histones only (d) Nucleotides Answer: (b) DNA and Histones