unit 2 Multicellular organisms

Question 1

what are the stages of mitosis

Answer 1

1. chromosones double to form two idnetical chromatids
2. they line up at the equator of the cell
3. spindle fibres attatch to the chromatids
4. The chromatids get pulled appart by the spindle fibres to different poles of the cell
5. a new nucleus is then formed at each pole of the cell.
6. two genetically identical cells are made with the correct chromatid number.

Question 2

What is a feature of stem cells

Answer 2

They are unspecialised & divide by mitosis

Question 3

Name the neurons

Answer 3

Sensory, inter and motor

Question 4

What is the gap inbetween called

Answer 4

Synapse

Question 5

How do the nuerons pass the message over the gap

Answer 5

Using diffusion of chemicals

Question 6

What does the cerebellum do

Answer 6

Controls balance

Question 7

What does the cerebrum do

Answer 7

Controls thought, emotions and memory

Question 8

What does the medulla do

Answer 8

Controls breathing

Question 9

what does a reflex action provide

Answer 9

Rapid automatic protection

Question 10

Explain the process of fertalisation

Answer 10

The nucleas of the male gamete fuses with the nucleus of the female gamete

Question 11

What are alleles

Answer 11

Different types of genes

Question 12

What is the reason for an unpredicted ratio

Answer 12

The diffusion of gametes is a random process

Question 13

what is it called when water diffuses through the stomata

Answer 13

Transpiration

Question 14

What are two types of white blood cell

Answer 14

lymphocytes & phagocytes

Question 15

What is the function of phagocytes

Answer 15

Engulf & digest

Question 16

What is the function of lymphocytes

Answer 16

Produce antibodies which destroy pathogens

Question 17

How are hormones released

Answer 17

endocrine glands

Question 18

What is the sight on gamete production in plants

Answer 18

Anther for male gametes and ovule for female gametes

Question 19

What is the result of fertalisation

Answer 19

A doploid zygote

Question 20

Give an example of descreate variation

Answer 20

Eye colour & blood type

Question 21

Give an example of continuous variation

Answer 21

Height & Weight

Question 22

Explain the process in which a plant absorbes water from the ground and evaporates it

Answer 22

The root hair cells absorb the water in the ground
The water then goes from the root hair cells to the xylem vessels by osmosis
The water then moves into the mesophyll layer where it can be used for photosynthesis
Some of the water then evaporates into the air spaces in the leave and then diffuses out into the air through the stomata

Question 23

Give the features of a xylem vessel

Answer 23

dead

rings of lignin for strength

Question 24

Give the features of phloem vessels

Answer 24

Living
Has a companion cell and a sieve tube
Contains sieve plates
Carry sugar

Question 25

What affects the rate of transpiration

Answer 25

Humididty Temperature Wind speed surface area

Question 26

What do red blood cells transport around the body

Answer 26

Oxygen

Question 27

What makes them good for transporting oxygen

Answer 27

Biconcave shape for larger surface area for oxygen to diffuse Contain lots of heimoglobin Dont have a nucleus so more room for heimoglobin

Question 28

Heimoglobin

Answer 28

where the oxygen concentration is high, heimoglobin joins with oxygen to form oxyheimoglobin and where the oxygen conenctration is low, heimoglobin relases oxygen.

Question 29

The pathway of blood in the heart

Answer 29

Deoxygenated bloof comes in through the vena cava, to the right atrium, through a valve to the right ventricle, out the pulmonary artery to the lungs. Oxygenated blood then comes in throught the pulmonary vein, to the left atrium, through a valve and into the left ventricle, and then out through the aorta to the body.

Question 30

What provides the heart with oxygen

Answer 30

Coronary arteries

Question 31

The features of arteries

Answer 31

Carry blood away from the heart | Thin with thick walls becuase they have to carry blood under high pressure

Question 32

Features of veins

Answer 32

Carry blood towards the heart wide central chanel and thin walls in order to carry more of it Contain valves to prevent the backflow of blood

Question 33

Features of capilaries

Answer 33

Tiny, thin walles vessels | Large surface area to allow the exchange of materials

Question 34

Features of alveoli

Answer 34

Large surface area allowing more diffusion One cell thick allowing quick diffusion Surrounded by capillares to provide effective diffusion Outiside is moist as they must dissolve in order to diffuse Oxygen going in, Carbon dioxide coming out

Question 35

Features of villi

Answer 35

``` Found in the small intenstine Increase surface area Have capillaries in them Fatty acids go into the lacteal Glucose & Amino acids into the capillaries ```

Question 36

What is pollygenic inheritance

Answer 36

When several genes contribute towards the variation giving a range of values