Cell Division

Question 1

Define cell continuity

Answer 1

All cells develop from pre-existing cells

Question 2

What are chromosomes made up of?

Answer 2

40% DNA and 60% protein

Question 3

How many chromosomes do human cell in each body cell (except for gametes)?

Answer 3

46

Question 4

How many chromosomes are in a gamete?

Answer 4

23

Question 5

Define chromatin

Answer 5

Long, thin strands when chromosomes are not dividing

Question 6

Draw a labelled diagram of the nucleus

Answer 6

See notes

Question 7

Define gene

Answer 7

Short strand of DNA that codes for a protein/unit of inheritance

Question 8

What do all the genes make up?

Answer 8

Genome

Question 9

Give some examples of what genes control

Answer 9

• Hair colour
• Shape of face
• Skin pigment

Question 10

What kind of proteins are produced in cell division?

Answer 10

Enzymes

Question 11

What is the metabolic role of a protein?

Answer 11

Enzymes

Question 12

Define haploid

Answer 12

One set of chromosomes - 23. n=23

Question 13

Define diploid

Answer 13

Two sets of chromosomes - 46. 2n=46. Chromosomes are in pairs

Question 14

Give an example of a diploid

Answer 14

Somatic cells (non-sex cells)

Question 15

Define triploid

Answer 15

Three sets of chromosomes

Question 16

Define homologous pair

Answer 16

A pair of chromosomes that each have genes for the same features at the same positions.

Question 17

In diploids, where does each chromosome come from

Answer 17

One from the mother and one from the father

Question 18

Define mitosis

Answer 18

Cell division. One nucleus divides to form two nuclei each containing the same number of chromosomes with identical genes. Produces identical cells

Question 19

Define daughter cell

Answer 19

New cell formed by mitosis

Question 20

What are the four stages of mitosis in order?

Answer 20

Prophase, metaphase, anaphase and telophase

Question 21

Describe what happens in prophase

Answer 21

• Before nucleus divides
• Chromatin starts to condense/contract and become visible as double stranded (identical), held together at the centromere
• Nucleolus disappears
• Spindle fibres appear
• Nucleus membrane starts to break down
• 2n=4

Question 22

Draw a diagram to show prophase

Answer 22

See notes

Question 23

Describe what happens during metaphase

Answer 23

• Nuclear membrane breaks down
• Spindle fibres attached to each centromere from the pole
• Chromosomes line up at equator of the cell

Question 24

Draw a diagram to show metaphase

Answer 24

See notes

Question 25

Describe what happens during anaphase

Answer 25

* Spindle fibres contract causing the centromeres to split * Chromosomes are pulled to opposite poles

Question 26

Draw a diagram to show anaphase

Answer 26

See notes

Question 27

Describe what happens during telophase

Answer 27

* Chromosomes at each pole begin to lengthen and become hard to distinguish -> chromatin * Spindle fibers break down * Nucleolus begins to reform * A nuclear membrane forms around each clump of chromatin

Question 28

Draw a diagram to show telophase

Answer 28

See notes

Question 29

Describe cell division in plant cells

Answer 29

* Vesicles gather in area between nuclei * Cell plate forms as vesicles fuse together made of cellulose * Area between two plant cells called middle lamella * Cell wall prevents cleavage furrow from forming

Question 30

Show diagram to show cell division in plant cells

Answer 30

See notes

Question 31

Describe cell division in animal cells

Answer 31

* Small grove called a cleavage furrow appears in cell near the equator * This becomes deeper until it divides the cytoplasm into two identical cells

Question 32

Draw a diagram to show cell division in animal cells

Answer 32

See notes

Question 33

Define interphase

Answer 33

When the cell is not dividing

Question 34

How often does interphase occur?

Answer 34

80% of the time

Question 35

What happens to chromosomes during interphase?

Answer 35

* They are in chromatin form - elongated, only visible as a mass * In later stages chromosomes duplicate in preparation for mitosis

Question 36

What organelles does the cell produce during interphase?

Answer 36

* Mitochondria * Chloroplasts * Ribosomes * Centrioles

Question 37

What does the cell produce during interphase?

Answer 37

* **Organelles**: Mitochondria, chloroplasts, ribosomes, centrioles * Enzymes needed for growth - protein synthesis. * **Biomolecules**: Nucleic acid, protein, fat, carbohydrates

Question 38

What biomolecules does the cell produce during interphase?

Answer 38

* Nucleic acid * Protein * Fat * Carbohydrates

Question 39

What cellular reactions take place during interphase?

Answer 39

* Protein synthesis * Respiration * Photosynthesis * Growth * Replication

Question 40

Define meiosis

Answer 40

Cell division. One cell divides into four daughter cells each with half the number of chromosomes as the parent

Question 41

Where does meiosis occur in humans?

Answer 41

* In ovaries to make eggs * In testes to make sperm

Question 42

What are the functions of meiosis?

Answer 42

* Allows for sexual reproduction - two cells (gametes) join to form diploid zygotes * Allows for variation - cells that divide by meiosis are not identical

Question 43

What are the functions of mitosis in multicelluar organisms?

Answer 43

* Growth * Repair/replace tissues/cells

Question 44

What are the functions of mitosis in unicellular organisms?

Answer 44

Asexual reproduction - increases number of individuals

Question 45

What are some examples of unicellular organisms where mitosis is use as a form of asexual reproduction?

Answer 45

* Amoeba * Yeast

Question 46

Define cancer

Answer 46

When a group of cells lose the ability to control the rate of mitosis

Question 47

Define benign tumors

Answer 47

Not life threatening tumors

Question 48

Give an example of a benign tumor

Answer 48

Warts

Question 49

Define malignant tumors

Answer 49

May be life threatening tumors - can invade other cells

Question 50

What are some causes of cancer?

Answer 50

Carcinogens: * Cigarette smoke * Asbestos fibres * UV rays