Question

Question 26:

The principal microtubule-organizing center in animal cells is the ____________.

A. centromere.

B. cell cortex.

C. centrosome.

D. Z-Disc

Question 27:

Catenin proteins:

A. binds to desmosomes of epithelial cells.
B. support epithelial cells to the basal lamina

C. allow ions and small molecules to pass from one cell to another.
D. link cadherin to the actin cytoskeleton.

Question 28:

Meiosis produces:

A. four cells that are genetically identical and contain half as many chromosomes as the original   

     parent germ-line cell.
B. two genetically identical daughter cells.
C. two cells that are genetically identical and contain half as many chromosomes as the original    

     parent germ-line cell.
D. four cells that are genetically dissimilar and contain half as many chromosomes as the original

     parent germ-line cell.

Question 29:

When does recombination (crossing-over) occur?

A. Meiosis I
B. Meiosis II
C. Mitosis S Phase
D. Mitosis M Phase

Question 30:

Which epithelial cell junctions serve to seal neighboring cells together so that water-soluble molecules cannot easily leak between them?

A. Desmosomes
B. Gap junctions
C. Tight junctions
D. Adherens junctions

Question 31:

In which group do pathway similarities suggest that ancestral signaling molecules first evolved in?

A. Fungi

B. Prokaryotes

C. Echinoderms

D. Eukaryotes

Question 32:

Which statement is correct?

A. Wnt stands for Wildtype Notch Transcriptor.

B. The Wnt signalling pathway is not conserved between animal species.

C. Wnt signalling is involved in a large number of diverse biological processes.

D. The APC/GSK3/Axin complex directly binds DNA to regulate target gene expression

Answer 1

26) microtubule-organizing center in the animal cells is centrosome. centrosome duplicates during S phase and it moves to opposite poles during prophase and mitotic spindle originates from the centrosomes so the answer is C. centrosome.

27) catenins are proteins that link the cadherin in the adherens junctions to the actin in the cytosol so the answer is D. link cadherin to the actin cytoskeleton.

28) during S phase the DNA replicates so when the chromatin condenses to form chromosomes during prophase I each chromosome have 2 sister chromatids attached to each other at the centromere, then the homologous chromosomes pair up and genetic material is exchanged between the non-sister chromatids, so the chromatids of a chromosome will have different genetic composition, and these homologous chromosomes are separated during anaphase I, so the resulting daughter cells will get one of the homologous chromosomes it can be paternal origin or maternal origin so each daughter cells formed by meiosis I are different and during meiosis II these cells divides to 2 daughter cells total of four cells are formed. during meiosis II the sister chromatids are separated and each daughter cell formed after meiosis II are unique, so the answer is

D. four cells that are genetically dissimilar and contain half as many chromosomes as the original parent germ-line cell.

29) recombination is the exchange of genetic material between the non-sister chromatids this occurs during the prophase I of meiosis I so the answer is A) meiosis I.