Question

TRUE OR FALSE

4.    During the S portion of interphase the DNA making up each monad is duplicated, and the two sister chromatids remain together in the region of the dyad called the centromere.

5.__ Cytokinesis is the term used to identify the separation of the cytoplasm of an animal cell into two complete, separate cells through the action of microtubules, intermediate filaments and kinesin motor proteins.

6.__ Cells of both plants and animals have spindle fibers present during cellular division and these fibers are short microfilaments composed of the protein actin with associated myosin motor proteins.

7.__ Cytokinesis in animal cells undergoing mitosis might not occur and this results in the production of a cell with two nuclei, each with the diploid amount of monads present.

8.__ The process of cytokinesis in plant cells requires the correct function of myosin motor proteins and actin microfilaments.

9.__ Most fungi, animals and protists have a sexual life cycle that involves a clear representation of the alternation of generations.

10.__ Aneuploidies are usually the result of the nondisjunction of homologs during meiosis I or the nondisjunction of monads during meiosis II.

11.__ Most types (kingdoms) of eukaryotic organisms produce gametes as a result of meiosis of diploid mother cells.

12.__ Segregation of gene alleles occurs exclusively during the second meiotic division of plants and exclusively during the first meiotic division in animals.

13.__ When asexual reproduction occurs, the offspring produced have DNA from a single parental source and the offspring have less genetic variability than sexual reproduction.

14.__ The 23rd pair of chromosomes in humans are the sex chromosomes and females are heterogametic (2 types of sex chromosomes) while males are homogametic (1 type of sex chromosomes).

15.__ All members of the Plantae have both a multicellular haploid (gametophyte) and multicellular diploid (sporophyte) component of their sexual life cycle.

16.__The reduction division stage of meiosis is the second meiotic division (meiosis II) and this is when human cells go from a diploid state of 46 dyads to a haploid state of 23 monads.

17.__ A tetrad is composed of a homologous pair of dyad chromosomes that are involved in synapsis and crossing over may occur between homologous chromatids when the dyads are in this state.

18.__ A key function suggested for why organisms perform meiosis is as a mechanism of purifying selection and the removal of deleterious (mutated) genes.

19.__ The key event(s) in the transformation of organisms from the haploid component of their life cycle to the diploid component are the meiotic division of cells and production of gametes..

20.__ In female chickens you would find somatic cells with fully homologous pairs of chromosomes (monads) but in males there would be only mostly fully homologous pairs (monads) and one partially homologous pair the sex chromosomes.

Answer 1

4. True , reason is during the S phase the DNA replicates as a result the DNA contents doubles chromatids are formed but they are attached in the region of the centromere.

5.True , Reason : Cell cycle has two phases the Karyokinesis stage and the cytokinesis stage , karyon is nucleus , karyokinesis is division of nucleus and cytokinesis is the division of the cytoplasm .

6.True , actin and myosin are the important components of spindle fibres .

7.True , during mitosis post karyokinesis if cytokinesis does not take place then the cell will have two nucleus and each nucleus will have equal number of chromosomes as of the mother cell , which is diploid because mitosis is equational division and monad is present , monad is having only one DNA molecule , during anaphase the diads convert to monads .

8.True , reason is the process of cytokinesis is by the formation phragmoplast and spindle fibres will get agrregated in the region in the of the phragmoplast in the region of the phragmoplast so it is very important .

9.False , alternation of generations is clear in lower organisms not distinct in highre organisms like animals .

10. True , non disjunction will result in anenuploids .

11. True, gametes are the result of meiotic division , which will reduce the chromosome number to half .

meiotic division can only take place in the diploid cells

12.False , the segregation takes place during the meiosis I in both plants in animals .

13.True , asexual reproduction does not involve two parents , it involves only one parent so DNA will be from one parent only . and as there is no recombination there will be less genetic variation .

14.False , In humans males are heterogametic XY is males , and females are homogametic XX .

15.False , all the members of the plant does not have multicellular haploid gametes , In higher plants like angiosperms the gametes are unicellular.

16.False , the reduction division is in meiosis I anaphase , not meiosis II

17.True , tetrad includes two chromosomes which are homologous , and each chromosome of the homologous pair has two chromotids , so four chromatids include a tetrad .

18.False , the key function of meiosis to reduce the chromosomal number to half and to produce variation.

19.False , the haploid organism becomes by fertilization , not by the meiosis .

20.False , in fowls zz is male and zw is female.