Cell Division, Diversity And Organisation

Question 0

Definition of meiosis

Answer 0

Process of nuclear division that results in the formation of cells containing half the number of chromosomes

Question 1

Definition of mitosis

Answer 1

Process of nuclear division where two genetically identically nuclei are formed from one parent cell

Question 2

Comparing meiosis and mitosis: mitosis

Answer 2

Genetically identical
2 daughter cells produced
Occurs in all animal cells and only in meristem cells
No crossing
Asexual reproduction
2 cells produced
46 chromosomes (number stays the same)
Repairs cells

Question 3

Comparing mitosis and meiosis: meiosis

Answer 3

Genetically varied
4 daughter cells produced 
Occurs in sex cells
Crossing sometimes occurs 
Gametes created
Sexual reproduction
One nuclear division separating choromosomes
23 chromosomes (haploid cells produced)

Question 4

Stages of mitosis

Answer 4

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 6

Why do yeast cells not produce the calculated number of potential new cells?

Answer 6

Mutations can occur

Bugles do not form exactly side to side

Question 7

Prophase

Answer 7

• Chromosomes condense
• Chromosomes can be seen at the centromere
• Nuceoli dissapears
• Nuclear membrane breaks down
• Spindle apparatus appears

Question 8

Metaphase

Answer 8

• Centromeres of chromosomes line up at equator
• Spindle apparatus is fully formed
• Sister chromatids are connected to either pole

Question 9

Anaphase

Answer 9

• Centromeres seperate
• Chromatids are drawn to either pole
• The movement is brought about by the lengthening of pole-pole microtubules and the shortening of pole-chromatid microtubules

Question 10

Telophase

Answer 10

• Daughter cells reach either pole
• Nuclear membrane and nucleoli reform
• Spindle apparatus disappears

Question 11

Cytokinesis (animal cells)

Answer 11

• Can occur after or during telophase

- Animal cells form a cleavage furrow where the cell is pinched off in two

Question 12

Cytokinesis (plant cells)

Answer 12

• Membrane bound vesicle containing cell wall material collect at the middle point
• Vesicles join to form a cell plate
• The cell plate extends to fuse with the plasma membrane, thus dividing the cells

Question 13

Binary fission

Answer 13

• Daughter cells are cloned
• DNA is circular and plasmids replicated, producing exact copies
• DNA is shared between daughter cells
• Not mitosis
• A colony of cells is produced by one single cell

Question 14

Budding yeast

Answer 14

• Produces genetically identical cells
• Nucleus divides
• Cell bulges on one side
• Bulge contains cytoplasm, organelles and one of the nuclei
• Bulge pinches off forming a cell wall around a new separate cell

Question 15

Stem cells

Answer 15

Undifferentiated cells that have the potential capability of becoming any one of the cell types in a fully grown organism

Question 16

Clones

Answer 16

Genetically identical cells or individuals

Question 17

Interphase

Answer 17

• DNA replicates
• DNA is decondensed so chromosomes are not visible
• Nuclear membrane and centrioles visible

Question 18

Importance of producing new cells

Answer 18

• Asexual reproduction
• Growth
• Repair
• Replacement

Question 19

Process of mitosis

Answer 19

• Chromosomes become visible
• Nuclear envelope breaks down
• Centrioles move to either pole and form a spindle
• Chromosomes line up at the equator
• Replicated sister chromatids split by their centromeres and move away towards the poles attached by their centromeres
• Nuclear envelopes surrounds new sister chromatids
• Spindle apparatus breaks down
• Cytokinesis takes place

Question 20

The cell cycle

Answer 20

Describes the events that take place as one parent cell divides to produce two new daughter cells which then each grow to full size

Question 21

Steps of the cells cycle

Answer 21

M – nuclear division (mitosis) + cytokinesis
G1 – Biosynthesis (proteins made, organelles replicated
S – Synthesis of new DNA (replication of new chromosomes
G2 – Growth

Question 22

Why can supercoiled chromosomes only be coiled for a short time

Answer 22

Supercoiled chromosomes can’t perform their normal functions in the cell so they need to be uncoiled

Question 23

How are cells in a multicellular organism organised?

Answer 23

• A group of specialised cells work together to form a tissue
• Groups of tissues carry out many processes to form an organ
• A group of organs that carry out a common process work together to form a organ system
• Cells differentiate to specialise in a specific function

Question 24

Processes that occur during interphase

Answer 24

• Cell growth (creation of organelles)
• Protein synthesis
• ATP production

Question 25

Ways in which plant cell division differs from animal cell division

Answer 25

• Cytokinesis in a plant occurs by cell plates fusing with membrane while cells are pinched off in animals
• Cytokinesis starts from the middle of the cell in plants
• Only occurs in meristem cells
• No centrioles in plants

Question 26

Why is genetic information copied and checked

Answer 26

If the genetic information is not checked mutations or errors in the genetic information may be further replicated

Question 27

Budding

Answer 27

• A bulge forms on the surface
• The nucleus and cytoplasm move into the bulge
• The bulge is pinched off
• Nucleus divides

Question 28

How is the ultrastructure of a neutrophil specialised for its function

Answer 28

• Contains many lysosomes that secreate enzymes that digest foreign cells
• Has a rough endoplasmic reticulum
• Has many ribosomes
• Much Golgi
• Cytoskeleton for transport
• Lots of receptors in surface membrane