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Question
How does colchicine act as mitotic poison? Is there any advantage of it?
Solution
Colchicine is an alkaloid obtained from Autumn crocus (Colchicum autumnale). It inhibits the formation of mitotic spindle. As a result, chromosomes duplicate but they remain within the same cell, increasing in number (endoduplication). Such cells are called polyploid cells.
Its advantage is that plant breeders have used colchicine-induced polyploidy as a means of producing variants of agricultural and horticultural crops.
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RELATED QUESTIONS
Chromosomes get aligned at the centre of the cell during:
A. Metaphase
B. Anaphase
C. Prophase
D. Telophase
Match the events given in column A with the phase in mitotic cell division in column B.
| Column ‘A’ | Column ‘B’ | ||
| 1. | Chromosomes get arranged in a horizontal plane at the equator. |
a. | Anaphase |
| 2. | Daughter chromosomes move to the opposite poles of a spindle |
b. | Prophase |
| 3. | Chromosomes become visible as fine, long threads. |
c. | Telophase |
| 4. | Chromosomes lose their distinctiveness and gradually become transformed into a chromatin network. |
d. | Metaphase |
State the difference between:
Chromosome and chromatid:
Answer the following question in your own words.
What is meant by ‘chromosome’?
Choose the correct answer:
Chromosome is most coiled at (in mitosis) ____________
Choose the correct answer:
Centromere is related to _______________
Choose the correct answer:
During mitosis which of the following disintegrate ___________
Write a sentence of the following:
Sheath
Choose the correct answer:
Chromosomes are thin and thread like at __________
Write the functional activity of the following structure:
Spindle fibers
Name the following:
Cells having a single set of chromosomes.
Complete the following sentence with appropriate word:
The chromosomal theory of inheritance was proposed by ____________in 1902.
Long answer type question.
Describe the different types of chromosomes.
Identify the odd one:-
The region of the chromosome where the spindle fibres get attached during cell division ______
The loss of one or more chromosomes in ploidy is called ______.
Match the following.
| 1. Autosomes | - | Trisomy 21 |
| 2. Diploid condition | - | 9 : 3 : 3 : 1 |
| 3. Allosome | - | 22 pair of chromosome |
| 4. Down’s syndrome | - | 2n |
| 5. Dihybrid ratio | - | 23rd pair of chromosome |
Explain the structure of a chromosome.
After a mitotic cell division, a human female cell will have ______.
