cells and control

Question 1

What are cells which possess both pairs of chromosomes called

Answer 1

Diploid

Question 2

What are cells that only contain one pair of chromosomes called?

Answer 2

Haploid cells (eg. sex cells, gametes)

Question 3

How do chromosomes divide?

Answer 3

-start as a parent chromosome
-split into 2 identical copies (sister chromatoids) but are still attached together at the centre
-sister chromatoids spilt apart and are now called daughter chromosomes

Question 4

what is interphase?

Answer 4

-INTERPHASE= cell is growing in size and creating more organelles (mitochondria, ribosomes, DNA) for when it splits.

Question 5

What is prophase

Answer 5

-PROPHASE= Chromosomes condense, becoming visible. Nuclear envelope breaks down, allowing chromosomes to move around in the cell. Centrioles move to opposite poles of the cell

Question 6

What is metaphase

Answer 6

-METAPHASE= Chromosomes line up in the middle. They are moved by spindle fibres which connect the sister chromatoids to the centrioles

Question 7

What is anaphase

Answer 7

-ANAPHASE= spindle fibres shorten, separating the sister chromatoids to the sides of the cell (now they are daughter chromosomes)

Question 8

What is telophase?

Answer 8

-TELOPHASE= New nuclear envelope forms around daughter chromosomes at either side of the cell. Forms 2 new daughter nuclei

Question 9

What is Cytokinesis

Answer 9

-CYTOKINESIS= The cytoplasm separates, forming 2 identical daughter cells

Question 10

order of mitosis?

Answer 10

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 11

how is cancer caused

Answer 11

some cells lose control of their cell cycle and keep rapidly dividing, producing masses of undifferentiated cells (tumours).
Tumours may spread and destroy organs

Question 12

how to treat cancer

Answer 12

-cut out the tumour if possible
-chemotherapy (take drugs which are toxic to rapidly dividing cells)
-radiotherapy

Question 13

what is a zygote

Answer 13

fertilised egg cell

Question 14

how does an egg develop into an adult

Answer 14

-egg cell is fertilised
-egg cell goes through mitosis, producing undifferentiated cells (embryo)
-cells in embryo switch in genes to differentiate into specialised cells

Question 15

what is a plant meristem

Answer 15

-groups of undifferentiated cells at the tips of roots/shoots
-allow the plant to grow until death

Question 16

where are the xylem and phloem in

Answer 16

vascular bundle (shoot)

Question 17

what does xylem do

Answer 17

carry water from roots to stem and leaves.
comprised of dead cells

Question 18

what does phloem do

Answer 18

transport dissolved sugars from leaves to where the plant needs it for growth or other processes

Question 19

what is a stem cell

Answer 19

an unspecialised cell that produces a different type of specialised cell

Question 20

What is the CNS

Answer 20

-brain and spinal chord
-allows us to respond to stimuli and to move

Question 21

What is the PNS

Answer 21

peripheral nervous system
-contains sensory and motor neurones
-sensory carries info to CNS about stimuli
-motor carries info from CNS to muscles and glands

Question 22

what are synapses

Answer 22

junctions where neurones communicate with eachother

Question 23

how do electrical impulses travel between neurons

Answer 23

-nerve impulse reaches end of neurone
- neurotransmitter releases chemicals which diffuse across synaptic gap
-chemical diffuses down conc gradient and binds to start impulse in the cell

Question 24

what do synapses do

Answer 24

slow the passage of information, ensuring that impulses only travel in one direction. This is because only one end of a neurone can make the chemical after receiving electrical impulse

Question 25

what are reflex actions

Answer 25

involuntary actions to protect us from harm. they are extremely fast because the brain is not involved and they only use 2/3 neurones (sensory and relay)