Cell division

Question 1

What happens in M phase

Answer 1

A checkpoint chemical triggers condensation of chromatin

Cell growth stops
Nuclear division occurs

Question 2

What happens in g0

Answer 2

Resting pahse of the cell

The cell may undergo apoptosis (planned cell death)
some cells remain in g0 for bleddy ages

Question 3

What happens in g1

Answer 3

Checks: checks that the cell is ready for S

the cell and all organelles grow and multiply

Question 4

What happens in S

Answer 4

All genes are checked

Once this begins the cell has committed to the cell cycle
This phrase is fast to avoid expose dna being out for long

DNA replicates

Question 5

g2

Answer 5

cell grows

Chemicals check the the replicated genetic information is all good yk and that it isn’t bad u get me

Question 6

What is the significance of mitosis

Answer 6

Asexual reproduction

Growth

Repair

Question 7

Phrophase

Answer 7

The chromosomes that have replicated during s phase now shorten and supercoil
The nuclear envelope breaks down
The centrioles move to opposite ends of the cell
Spindle fibres form

Question 8

Metaphase

Answer 8

Pairs of chromosomes attach to spindle fibres by their centromere

Question 9

Ananpahse

Answer 9

The centromere of each pair of chromatids splits
motor proefins pull the chromatids top opposite ends of the cell
Chromatids are now called chromosomes

Question 10

Telophase

Answer 10

Nuclear envelopes reform around each set of chromatids
The cell now contains 2 sets of genetic info and divides via cytokinesis

Question 11

Cytokinesis

Answer 11

In animal cells the membrane folds in a tucks in the cytoplasm

in plant cells an end plate forms where the equator spindle was and a new plasma membrane is built on it

Question 12

What is the significance of meiosis

Answer 12

Genetic variation
Evolution
Disease resistance

Question 13

What are the stages of meiosis

Answer 13

Prophase 1 (crossing occurs between chromatids)

Metaphase 1 (Pairs are arranged randomly )

Anaphase 1 (Centromeres do not divide each chromosome consists of 2 chromatids)

Telophase 1 (Half the amount of original chromosomes but 2 of each)

Prophase 2

Metaphase 2 (attach by centromeres random arrangement)

Anaphase 2 (Centromeres divide and pulled apart)

Telophase 2 (Nuclear envelope reforms (4 cells ))

Question 14

How does meiosis produce genetic variation

Answer 14

Crossing suffles chromosomes

random assortment of chromosomes in anaphase

Haploid gametes are produced that are combined to form zygote

Question 15

What is a zygote

Answer 15

Spunk + egg

Question 16

What is a gamete

Answer 16

Result of meiosis (half info)

Question 17

What is the need for cell differentiation

Answer 17

specific organelles such as red blood cells need to be produces

Question 18

What is differentiation

Answer 18

An undifferentiated cell has the possibility too activate any gene in the genome and become any cell. Theses are stem cells and they can divide by mitosis

These cells genes get activated or dis activated depending on the function of the cell. This changes the makeup of the cells and it becomes specialised

Question 19

What is an erythrocyte and how is it specialised

Answer 19

Carry o2 in the blood, biconcave, no nucleus, small, large sa:v

Question 20

What is a neutrophil and how is it specialised

Answer 20

Ingest pathogens, Large, multi lobed nucleus, travel towards infection

Question 21

What are spermatozoa and how are they specialised

Answer 21

Carry gametes to the egg

Long flagellum from transport

lots of mitochondria

acrtosome containing enzymes to break down the egg wall

Question 22

What are epithelial cells and how are they specialised

Answer 22

Lining tiisuew

Flat in shape

Can contain cilia for wafting mucus etc

Question 23

Palisade cells

Answer 23

Long and cylindrical in shape so they ca pack tightly together

Large vacuole so that chloroplasts are closer to the surface

Many chloroplasts

Question 24

Guard cells

Answer 24

Potassium ions actively transported from the surroundings lowering their water potential

This forces water to osmosis into the cells

This rises the flexible tips to expand and causes them to open up

This allows air into the cell

Question 25

Root hair cells

Answer 25

Hair like projections to increase surface area

mineral ions are actively transported into the ell to decrease the water potential

Many carrier proteins to achieve this

Question 26

Epithelial tissue

Answer 26

Covers and lines surfaces in the body

Entirely made up of cells

No blood vessels

can contain villi

Question 27

What are the 4 types of tissue

Answer 27

epithelial

Connective – cartialge

Muscle

nervous

Question 28

What are the types of cartilage

Answer 28

Hyaline, covers the ends of long bones and joins the ribs

Fibrous, discs between vertebrae

Elastic, makes up ears and nose

Question 29

Muscle tissue

Answer 29

Very well vascularised and have many mitochondria in order to release energy

Many muscle fibres that contain action and myosin to bring about movement

Question 30

Types of muscle

Answer 30

Skeletal ( movement )

Cardiac ( heart )

Smooth (lines arteries and branch )

Question 31

Xylem

Answer 31

water and minerals

Lignified cell walls, dead cells , cell ends broken down to form a long tube

Question 32

phloem

Answer 32

sucrose and glucose

Sieve tubes on the end of cells

companion cells to produce ate

Question 33

What is the flower for

Answer 33

sexual reproduction

Question 34

What is the stem for

Answer 34

Support, transportation
Storage

Question 35

What are the sources of stem cells

Answer 35

Embryos
Umbilical chord
bone marrow
Meristem

Question 36

Bone marrow transplant

Answer 36

External bone marrow is extracted and used to treat blood diseases such leukaemia

Question 37

Use of drug cells to replace any cell

Answer 37

Extract and activate the oreect genes to differentiatee that cell onto the the desired one