Chapter 8
Exercises page 165
11- a → chromosomes are visible
b → asters appear in animal cells
2- a → are always made up of chromatin
b → represent the carriers of genetic information
e → are duplicated during interphase
3- b → always begins after interphase
4- b → receives the whole genetic information
2a- centromere → 2- place where chromatids join
b- mitosis → 1- cellular division leading to 2 cells possessing same karyotype as original cell
c- chromatids → 4- filaments resulting from duplication of chromosomes
d- conformed reproduction → 3- duplication of chromosomal material
3a- True
b- False, have the same karyotype
c- True
d- True
e- False, only during mitosis
4a- During interphase, simple chromosomes undergo duplication to become double
chromosomes.
b- During cellular division, the mother cell containing double chromosomes divides into 2
daughter cells containing simple chromosomes.
c- The nucleus contains chromosomes which carry genetic information.
5c→a→d→b
6Zygote, genetic information
Identical
Duplication, interphase
Chromatids, poles
Transmission, distribution, karyotype
7Phase of mitosis
anaphase
prophase
metaphase
anapahase
telophase
prophase
prophase
telophase
prophase
Events
separation of chromatids
appearance of asters
chromosomes line forming equatorial plate
chromatids move towards opposite poles
constriction of cytoplasm
disappearance of nuclear membrane
appearance of achromatic spindle
formation of two daughter cells
appearance of double chromosomes
8a- Metaphase, since the chromosomes are lined on the equator forming the equatorial
plate.
b- 1 → aster
2 → achromatic spindle
3 → chromatids
c-
9a-
b- During anaphase, the 2 chromatids of each chromosome separate, and move towards
opposite poles forming polar ascension.
10a- b → d → a → c
b- ‘a’ : Anaphase
Chromatids of each chromosome separate and move to opposite poles
‘b’ : Prophase
Chromosomes with double chromatids appear
Appearance of nuclear membrane
‘c’ : Telophase
Constriction of cytoplasm
Two daughter cells appear
‘d’ : Metaphase
Chromosomes line forming equatorial plate
c- During prophase, the chromosome has double chromatids. Same for metaphase. During
anaphase, the chromosome has 1 chromatid after separation, and remains the same
during telophase.
d- During interphase that separates two successive divisions, each cell duplicates its
chromosomes, hence the genetic information is also duplicated.
During mitosis, the chromosomes separate and each pair goes into a daughter cell, thus
each gets a copy of the same genetic information which remains conserved.
11a-
b- Each daughter cell should undergo interphase to duplicate its chromosomes and get
ready for mitosis. This occurs in order to maintain and conserve the genetic information.