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1.
Draw diagrams to show the four stages of mitosis in an animal cell with four chromosomes.
(Total 5 marks)
2.
Outline the differences between the behaviour of the chromosomes in mitosis and meiosis.
(Total 5 marks)
3.
(a)
Define the term sex linkage.
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(1)
(b)
A male and female with normal colour vision each have a father who is colour blind.
They are planning to have children. Predict, showing your working, the possible
phenotypes and genotypes of male and female children.
Key
male
female
affected male
affected female
?
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(3)
1
(c)
Explain the relationship between Mendel’s law of segregation and meiosis.
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(3)
(d)
Distinguish the differences between animal cells and plant cells undergoing mitosis and
cytokinesis.
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(2)
(Total 9 marks)
4.
Colchicine is a chemical substance that prevents the formation of microtubules. What stage of
mitosis would be prevented, if dividing cells were treated with colchicine?
A.
Breaking down of the nuclear membrane
B.
Replication of DNA
C.
Separation of genetically identical chromosomes (chromatids)
D.
Supercoiling of chromosomes
(Total 1 mark)
2
5.
Which of the following processes take place during interphase?
I.
Respiration
II.
Active transport
III.
Protein synthesis
IV.
Replication of DNA
A.
I only
B.
I and II only
C.
I, II and III only
D.
I, II, III and IV
(Total 1 mark)
6.
If a cell plate is beginning to form and nuclei are re-forming at opposite ends of a cell, what
kind of cell is this?
A.
An animal cell in prophase
B.
A plant cell in prophase
C.
An animal cell in telophase
D.
A plant cell in telophase
(Total 1 mark)
7.
Which statement is characteristic of tumours?
A.
They occur only in certain animal cells.
B.
They result from controlled cell division in only some organs.
C.
They result from uncontrolled cell division and occur in any organ.
D.
They result from partially controlled transcription.
(Total 1 mark)
3
8.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
Before cell division in unicellular and multicellular organisms, the nucleus must divide to
produce two genetically identical nuclei. Explain the events that occur in cells that result
in the production of genetically identical nuclei.
(8)
(b)
Cell division in unicellular organisms can increase the population size. Outline reasons
for the population of a unicellular organism not increasing, despite reproduction by cell
division.
(6)
(c)
Suggest why cell division is necessary in multicellular organisms.
(4)
(Total 20 marks)
9.
What is the product of mitosis in plant cells?
A.
Four daughter cells with genetically different nuclei
B.
Four daughter cells with genetically identical nuclei
C.
Two daughter cells with genetically different nuclei
D.
Two daughter cells with genetically identical nuclei
(Total 1 mark)
10.
What ensures that mitosis produces two genetically identical nuclei?
A.
One of each of the twenty-three types of chromosome is pulled to each pole of the cell by
spindle microtubules.
B.
Half of the chromosomes are pulled to each centriole by mesosomes.
C.
Identical chromatids are pulled to opposite poles by spindle microtubules.
D.
DNA molecules are moved to the equator of the cell where they are replicated.
(Total 1 mark)
4
11.
(a)
Variation occurs at the species level. Explain how sexual reproduction promotes variation
in species.
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(2)
(b)
Living organisms are classified according to their characteristics using a hierarchy of
taxa. State the missing taxa in the table below.
Levels in the hierarchy of classification taxa
(i) .......................................................................
Phylum
(ii) .......................................................................
(iii) .......................................................................
Family
(iv) .......................................................................
Species
(2)
5
(c)
Explain how differentiation results in a variety of different types of cells occurring in a
multicellular organism.
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(3)
(Total 7 marks)
12.
The DNA of a particular cell is damaged, so that the cell continues to divide uncontrollably.
What is the possible result?
A.
Coronary heart disease
B.
AIDS
C.
Tumour formation
D.
Down syndrome
(Total 1 mark)
13.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
Draw and label a diagram of the ultrastructure of a liver cell.
(4)
(b)
Explain how mitosis produces two genetically identical nuclei.
(8)
(c)
Outline one therapeutic use of stem cells.
(6)
(Total 20 marks)
6
1.
prophase showing spindle fibres;
prophase showing condensed chromatin;
prophase showing replicated chromosomes;
metaphase showing replicated chromosomes lining up at the equator;
anaphase showing chromatids moving to opposite poles;
telophase showing nucleus reforming;
telophase showing cytokinesis occurring;
The four diagrams must have the name of the phase, otherwise award [3 max].
The four stages must be included to receive [5]. If correct number of
chromosomes is not shown award [4 max].
5 max
[5]
2.
two divisions in meiosis, only one in mitosis;
meiosis results in haploid cells, mitosis in diploid cells;
crossing over only occurs in meiosis;
no S phase precedes meiosis II;
chromosome behaviour in meiosis II and mitosis is similar / chromosome
behaviour in meiosis I and mitosis is different;
chiasmata only form during meiosis;
homologous chromosomes move to the equator in pairs only in meiosis;
Do not accept number of cells produced - it is a result not a behaviour.
[5]
3.
(a)
genes found on the sex chromosomes / X / Y chromosome
Characteristics or traits are unacceptable replacement for genes.
1
(b)
parent genotypes (XCY and XCXc) / same genotypes using alternative symbols /
four offspring genotypes (XCXc, XCXC, XCY,XcY);
Punnett square showing cross / other acceptable working;
all / 100% daughters normal colour vision (phenotype);
half / 50% the sons normal and half / 50% are colour blind (phenotype);
3 max
Award [0] for autosomal analysis.
(c)
law of segregation states that one half of the alleles enter one gamete
and the other half enter the other gamete;
meiosis reduces the chromosome number by half / diploid to haploid;
homologues carrying alleles separate (in anaphase I);
end result is four cells, half with one allele / homologue and the other half
with the other allele;
3 max
7
(d)
plant cells lack centrioles / animals cells have centrioles;
plants form a cell plate / new cell wall to divide cells / animal cells from
a cleavage furrow;
2
[9]
4.
C
[1]
5.
D
[1]
6.
D
[1]
7.
C
[1]
8.
(a)
mitosis;
DNA replication;
each chromosome consists of two sister / identical chromatids;
chromosomes condense / supercoiling;
nuclear membrane breaks down;
chromosomes align (at equatorial plate);
spindle fibres / microtubules attach to centromeres of chromosomes on opposite
sides;
centromeres split;
chromatids become chromosomes;
sister / identical chromosomes pulled to opposite poles;
nuclear membranes reform;
events correctly assigned to interphase, prophase, metaphase,
anaphase, and telophase;
8 max
NB:
A correct sequence of idea should be recognized when
awarding the quality mark for structure of the answer
(linked ideas).
8
(b)
mortality / cell death;
emigration;
rate of death / mortality equal to or greater than cell division / reproduction;
predation / example of predator / macrophage;
disease;
competition for food / other resources;
food running out;
accumulation of waste products;
change in pH;
change in temperature;
antibiotics:
change in the growth medium;
lack of oxygen / carbon dioxide;
6 max
(c)
more cells needed for growth;
repair / replacement;
cells specialize / differentiate for particular functions;
formation of reproductive cells (meiosis);
cells have to divide when they reach a certain size;
surface area to volume ratio becomes too small;
materials / oxygen / named material cannot be absorbed quickly enough;
rate of use of materials related to volume but rate of exchange related
to SA;
4 max
(Plus up to [2] for quality)
[20]
9.
D
[1]
10.
C
[1]
11.
(a)
meiosis;
random fertilization;
half the genetic information comes from each parent;
independent assortment / crossing over;
2 max
9
(b)
(c)
(i)
kingdom;
(ii)
class;
(iii)
order;
(iv)
genus;
Award [2] if all four are correct [1] if three correct and
[0] if only two or one correct.
cells specialize;
all carry the same genetic information;
some genes are expressed / switched on;
other genes are suppressed / switched off / not expressed;
follow a developmental pathway;
position of the cell in the developing organism determines the type
of cell it differentiates into;
2 max
3 max
[7]
12.
C
[1]
13.
(a)
Award [1] for each structure clearly drawn and correctly labelled.
nucleus-smaller area than cytoplasm, surrounded by double membrane
with pores;
mitochondrion-surrounded by double membrane, inner membrane has
infoldings;
rough endoplasmic reticulum-stacked tubules with dots / small circles
on outer surfaces;
Golgi apparatus-curved stacked tubules, small vesicles near ends of
tubules / sacs;
ribosomes both attached to rER and free ribosomes in cytoplasm drawn
and labelled;
lysosome / nucleolus / nuclear envelope / nuclear pore / plasma membrane; 4 max
Award [0] if a plant cell is drawn.
Award [3 max] if a plant cell structure (such as the cell wall) is
present.
10
(b)
during interphase DNA replicates / produces two copies of genetic material;
sister chromatids are two identical DNA molecules held together by centromere;
sister chromatids are separated during mitosis to form two genetically
identical nuclei;
in prophase chromosomes shorten / thicken / become visible as double-stranded
chromosomes / joined sister chromatids;
chromosomes condense by supercoiling;
chromosomes attach to spindle microtubules at centromeres;
chromosomes begin to move towards equator / centre of cell;
during metaphase all chromosomes lined up at equator separately / not in
homologous pairs;
at start of anaphase centromeres divide separating sister chromatids;
separated sister chromatids known as (single stranded) chromosomes;
(identical sets of) chromosomes pulled to opposite poles;
move by contraction of microtubules;
nuclear envelope / membrane forms around each set of chromosomes;
8 max
Many of these points can be shown by correctly annotated
diagrams.
Credit may be given for diagrams clearly illustrating these
points.
11
(c)
Award [4 max] for any of the following general statements:
stem cells are cells that retain the capacity to divide and have the ability to
differentiate along different paths into all types of cells / are pluripotent / totipotent;
stem cells are derived from blastocysts / human embryos, left over from
IVF / placenta / umbilical cord / some adult tissues;
new techniques / technologies rely on replacing diseased / dysfunctional cells with
healthy / functioning ones;
need to identify desired type of stem cell and grow in culture / special
solutions / controlled conditions;
develop biochemical solution that will cause cells to differentiate into desired
cell type;
develop means of implanting / integrating cells into patient’s own tissues so that
they function with the body’s natural cells;
danger of rejection of cells therefore need to suppress immune system;
must make sure new cells do not become overgrown / develop into
cancerous tumours;
Award [2 max] for a specific example ie: [1] for type of cells
and [1] for proposed use:
eg retinal cells;
replace dead cells in retina to cure presently incurable diseases such as glaucoma
and macular degeneration;
eg graft new skin cells;
to treat serious burn victims;
eg nerve tissue;
help repair catastrophic spinal injuries / help victims of paralysis
regain movement;
6 max
(Plus up to [2] for quality)
[20]
12