Cell division, Cell Diversity & Cellular Organisation

Question 1

Animal cells

Answer 1

Means of cell division- Cytokinesis
Presence of nucleus-yes
Material in cell wall-none
Presence if ribosomes-yes

Question 2

plant cells

Answer 2

Means of cell division- cytokinesis
Presence of nucleus- yes
Material in cell wall- cellulose
Presence of ribosomes-yes

Question 3

Yeast cells

Answer 3

Means of cell division- budding
Presence of nucleus-yes
Material in cell wall-chitin
Presence of ribosomes-yes

Question 4

Bacterium

Answer 4

Means of cell division-binary fission
Presence of nucleus-no
Material in cell wall-peptidoglycan
Presence of ribosomes-yes

Question 5

Type of tissue that undergoes cell division in tips of roots and shoots to form undifferentiated plant cells

Answer 5

Meristem

Question 6

Some Features not found in xylem vessel

Answer 6

Nucleus
Cytoplasm
Cross/end cell walls

Question 7

How structure of cell walls in xylem vessels would differ from the cell walls of the undifferentiated meristem

Answer 7

Thicker
Lignified
Contain bordered pits

Question 8

Two types of cells that can be found in phloem tissue

Answer 8

Sieve tube elements
Companion cells
+
Parenchyma

Question 9

Ways in which genetic variation is produced, including the role of nuclear division

Answer 9

A1. Independent assortment/random segregation of homologous chromosomes
A2.in, metaphase I/meiosis I
A3.of chromatids in,metaphase II/meoisis II
A4.So homologous chromosomes have different alleles
A5.produces large number of allele combinations

C1. Crossing over/formation of chiasmata
C2. In Prophase I/meiosis I
C3. So chromatids will have new combinations of alleles
C4.amount of variation depends on distance between crossover points

M1.mutation
M2.changes the (DNA) nucleotide/base sequence
M3.DNA checks during duplication did not recognise damage
M4.diferences in primary sequences

N1.non-disjunction
N2.homologous chromosomes do not seperate (In metaphase I)
N3. One, more/less ,chromosome present

F1.Random,mating/fusion of gametes/feetilisation
F2.gametes are not genetically identical
F3.produces large number of allele combinations

Question 10

Cell signalling

Answer 10

Communication between cells

Question 11

2 examples of communication between cells that occur during life cycle of D.discoideum

Answer 11

1.attraction of cells to folic acid from bacteria
2.attraction of cells to eachother bt cAMP
+
3.coordinated movement in grex
4.differentiation of grex cells in response to DIF

Question 12

Suggest how plasma membrane of D.discoideum is adapted for cell communication

Answer 12

Contains receptors/glycoproteins/glycolipids

For folic acid/cAMP/DIF

Question 13

Type of cell division in plant growth

Answer 13

Mitosis

Question 14

Metaphase

Answer 14

Four chromosomes on equator

Question 15

New growth in stem or trunk comes from cambium

Explain why the new branches are seen growing from abposition just under bark of cut suface

Answer 15

This is where cambium is found
Mitosis occurs in cambium to produce new cells for growth
New cells differentiate into xylem and phloem
Xylem supplies water for cell elongation/cell growth
Phloem supplies assimilates for energy/growth/respiration

Question 16

Name one other location where growth occurs in a plant

Answer 16

1.tip/apex of shoot/root
+
2.meristem
3.bud

Question 17

Lenticels allow gases to diffuse into living tissues of trunk
Suggest why lenticels are essential to the survival of large multicellular plants and explain why similar structures are not found in large multicellular animals

Answer 17

Allow oxygen to reach cells/tissues under bark
For aerobic respiration
Animals transport oxygen in blood/circulation/transport system
Plants do not transport much oxygen in transport system
Oxygen not supplied from leaves as stomata only open in day/no leaves in winter

Question 18

Link up

Answer 18

Independent assortment –> Metaphase I & II
Formation of the spindle aparatus –>Prophase I
Seperation of sister chromatids –> Anaphase 2
Formation of nuclear membranes –> Telophase II
Chromosomes pulled to opposite poles –> Anaphase 1

Question 19

Explain why meiosis needs to have twice as many stages as mitosis

Answer 19

To halve chromosome numbers/ have chromosome numbers reduce from 2n to n

To seperate homologous pairs of chromosomes and sister chromatids

Because DNA previously replicated/ chromosomes are.two chromotids at start

Question 20

What feature of DNA molecule is changed as a result of mutation

Answer 20

Sequence/order of bases/nucleotides

Question 21

Possible effects that mutation can have on the structure of a protein

Answer 21

Different primary/secondary/tertiary structure
Protein shorter due to deletion/stop codon OR
Longer due to insertion/duplication
Protein unchanged due to silent mutation
Function is lost/worse/better