Cell Division

Question 1

Definition of cell continuity?

Answer 1

means that all cells develop from pre-existing cells.

Question 2

What are chromosomes?

Answer 2

are coiled threads of DNA and protein.

Question 3

Humans have how many chromosomes in each body cell?

Answer 3

46.

Question 4

Discuss chromosomes when a cell is not dividing?

Answer 4

they exist as long, thin threads called chromatin.

Question 5

At cell division, chromatin…?

Answer 5

contracts to form a number of clearly distinguishable chromosomes.

Question 6

What’s a gene?

Answer 6

a section of DNA that contains the instructions for the formation of a protein.

Question 7

Definition of a haploid cell?

Answer 7

has one set of chromosomes.

Question 8

Definition of diploid cell?

Answer 8

has two sets of chromosomes.

Question 9

Haploid is symbolised by what letter?

Answer 9

n.

Question 10

Diploid is symbolised as what?

Answer 10

2n.

Question 11

What’s a homologous pair?

Answer 11

is two chromosomes of similar size with the same sequence of genes.

Question 12

The cell cycle describes what?

Answer 12

the life cycle of a cell.

Question 13

Definition of interphase?

Answer 13

state of non division.

Question 14

What’s the longest phase in the cell cycle?

Answer 14

interphase.

Question 15

Interphase accounts for over what % of the cycle?

Answer 15

90%.

Question 16

Name 4 things that happen in interphase?

Answer 16

• photosynthesis,
• respiration,
• DNA replication,
• protein synthesis.

Question 17

Definition of mitosis?

Answer 17

cell/nuclear division, forming two identical (daughter) cells.

Question 18

What’s the function of mitosis in unicellular organisms?

Answer 18

reproduction.

Question 19

What’s function of mitosis in multicellular organisms?

Answer 19

growth/repair of tissue.

Question 20

Name 4 human cells not produced by mitosis?

Answer 20

• sperm,
• egg,
• sex cell,
• gamete.

Question 21

What is cancer?

Answer 21

uncontrolled mitosis.

Question 22

What does benign mean?

Answer 22

kind.

Question 23

What happens in a benign tumour?

Answer 23

the cells stop dividing after some time.

Question 24

Are benign tumours life threatening? Why/why not?

Answer 24

no as they don’t invade other tissues.

Question 25

Give 2 examples of benign tumours and how they are caused?

Answer 25

- warts, caused by a virus. - skin 'tags', small blobs of raised skin.

Question 26

What cells form a malignant tumour?

Answer 26

abnormal cells.

Question 27

Are malignant tumours life threatening? Why/why not?

Answer 27

they can be as they can invade other cells and can move from one place to another in the body.

Question 28

The movement of malignant cells is called?

Answer 28

metastasis.

Question 29

What are oncogenes?

Answer 29

cancer-causing genes formed from altered normal genes.

Question 30

What are carcinogens?

Answer 30

cancer-causing agents.

Question 31

Name 3 common carcinogens?

Answer 31

- cigarette smoke, - asbestos fibres, - ultraviolet radiation.

Question 32

Name 3 treatments for cancer and describe them.

Answer 32

- surgery. - radiation: burn out cancer. - chemotherapy: use of chemicals that slow down mitosis.

Question 33

What's meiosis?

Answer 33

a form of nuclear division in which the four daughter nuclei contain half the chromosome number of the parent nucleus.

Question 34

3 functions of meiosis?

Answer 34

- produce gametes (for sexual reproduction). - allow for diploid number. - restore chromosome number.

Question 35

Give 2 reasons meiosis allows for variation?

Answer 35

- rearrange genetic material. - produces non-identical cells.

Question 36

Four stages of mitosis in order?

Answer 36

prophase, metaphase, anaphase, telophase.

Question 37

What starts to chromatin in prophase?

Answer 37

starts to contract early.

Question 38

What starts to contract in prophase?

Answer 38

chromatin.

Question 39

What become visible as double-stranded structures in prophase?

Answer 39

chromosomes.

Question 40

Chromosomes become visible as what in prophase?

Answer 40

double-stranded structures.

Question 41

The point at which the strands are attached in a double-stranded chromosome is called?

Answer 41

a centromere.

Question 42

The fibres that appear in the cytoplasm in prophase are called?

Answer 42

spindle fibres.

Question 43

In prophase the spindle fibres collectively form a structure called the what?

Answer 43

spindle.

Question 44

What happens the nuclear membrane in prophase?

Answer 44

starts to break down.

Question 45

What happens the nuclear membrane in metaphase?

Answer 45

completes it's breakdown.

Question 46

What happens the chromosomes in metaphase?

Answer 46

line up across the middle, or equator, of the cell.

Question 47

What happens the spindle fibres in anaphase? What does it cause?

Answer 47

spindle fibres contract causing the centromeres to split.

Question 48

What happens the chromosomes in anaphase?

Answer 48

pulled apart to opposite poles of the cell.

Question 49

What happens spindle fibres in telophase?

Answer 49

break down.

Question 50

What begin to re-form in telophase?

Answer 50

one or more nucleoli (singular: nucleolus).

Question 51

What forms around the chromatin at each end of the cell in telophase?

Answer 51

nuclear membrane.

Question 52

What happens at the end of mitosis in telophase?

Answer 52

divided into two identical nuclei.

Question 53

Cell division follows immediately after what?

Answer 53

mitosis.

Question 54

Cell division occurs in animals by a process called?

Answer 54

cleavage.

Question 55

What forms during cell division in animals?

Answer 55

cleavage furrow forms.

Question 56

What forms during cell division in plants?

Answer 56

plate forms.

Question 57

Differences between mitosis and meiosis?

Answer 57

Mitosis: 2 cells are formed. Meiosis: 4 cells are formed. Mitosis: daughter cells have identical genes on their chromosomes. Meiosis: daughter cells have different genes on their chromosomes. Mitosis: chromosome number stays the same. Meiosis: chromosome number is halved 2n-n.

Question 58

Describe prophase.

Answer 58

- at end of interphase/early prophase, chromatin starts to contract. - *chromosomes become visible as double-stranded structures*. The point at which the strands are held together is called a centromere.The two strands in a chromosome have identical genes, each strand is a chromosome. - fibres that are in cytoplasm are called spindle fibres. Collectively they *form a structure called the spindle*. - *nuclear membrane starts to break down*. - *double stranded*.

Question 59

Describe metaphase.

Answer 59

- nuclear membrane completes it's break down. - a spindle fibre from each end/pole of the cell attaches to each centromere. - chromosomes lineup across the middle or equator of the cell.

Question 60

Describe anaphase.

Answer 60

- spindle fibres contract. Causes the centromeres *to split*. - one strand/chromosome from each double-stranded chromosome is pulled to opposite poles of the cell. Meaning the cell has 8 chromosomes here. The 4 chromosomes pulled to each pole have identical genes.

Question 61

Describe telophase.

Answer 61

- the 4 chromosomes at each pole begin to lengthen and become hard to distinguish. - spindle fibres break down. - one or more nucleoli (sing: nucleolus) begin to re-form. - nuclear membrane forms around the chromatin at each end of the cell. - at end of mitosis the original nucleus has divided into 2 identical nuclei.

Question 62

Many of the proteins produced by genes are?

Answer 62

Enzymes

Question 63

All the genes in an organism make up its?

Answer 63

Genome

Question 64

Name some features controlled by genes in humans, then plants.

Answer 64

Eye colour, production of skin pigment. Petal colour, leaf shape

Question 65

Genes are said to be?

Answer 65

Units of inheritance

Question 66

Units of inheritance refer to?

Answer 66

Genes

Question 67

Name two haploid cells in humans.

Answer 67

Sperm and eggs

Question 68

What happens chromosomes in interphase?

Answer 68

Elongated

Question 69

Cells aren’t dividing in interphase but they are active, how so?

Answer 69

- Producing new organelles. Forms chemicals needed for growth - Chromosomes at the end produce identical copies of themselves. The duplication produces a chromosome with 2 strands which have identical genes.

Question 70

Mitosis takes place in what kind of cells?

Answer 70

Non-reproductive cells called somatic cells

Question 71

Meoisis occurs where in humans? Why there?

Answer 71

ovaries and testes to produce gametes (eggs and sperm).

Question 72

What's the centromere?

Answer 72

Point at which the chromosomes are attached in a double-stranded chromosome.