Polyploidy is generally better tolerated in animals than it

Polyploidy is generally better tolerated in animals than it is in plants.

An autotriploid could be produced by fertilization of an egg that failed to undergo meiosis and a normal sperm from the same species.

Autotetraploids almost always produce gametes with a balanced number of chromosomes.

A key step in the formation of a fertile allopolyploid requires doubling of the number of chromosomes in a cell.

Cells of an amphidiploid contain two separate diploid chromosome sets.

Polyploidization has occurred in the evolution of vertebrate genomes.

A tetraploid cell can be created by nondisjunction of all the chromosomes in a diploid cell.

Solution

1. False:

Polyploidy is less common in animals. Polyoloidy results in a genetic change in the animal where in chromosome number is increased. Because of this the animal has abnormal chromosome number and is incompatible with the original species. However in plants this is the most common phenomena and almost about two thirds of the plants are polyploids.

2. True

Autotriploids can arise from the fertilization of an unreduced egg (2n) by a normally reduced male gamete (n) of an originally diploid species.

3. False

In autotetraploids because 4 is an even number, they can have a regular meiosis, although this is not the case always. Because the chromosomes may either disjoin in 2:2 manner producing diploid gametes or they may disjoin in 3:1 manner.

4. True

Allopolyploids are formed from two different species.For example an allotetraploid between two species A and B will be formed if F1 hybrid (AB) undergoes chromosome doubling. Usually the hybrids between these two species are sterile because two unrelated chromosomes do not pair during meiosis.

5. True

Amphidiploids are a type of allopolyploids. They are allotetraploid and contain the diploid chromosome sets of both parents.

6. True

Polyploidy has occured in the early vertebrate evolution. Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization.

7. True

Polyploids can arise by abnormal mitosis. During abnormal mitosis chromosome of a dividing cell fails to separate or cell division stops after the duplication of chromosome. The cell thus produced is with double the number of chromosomes compared to the diploid parent cell. In this case tetraploidy occurs in the zygote.