Cells And Control 🧫

Question 1

What is diffusion?

Answer 1

Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration.

Question 2

What factors affect diffusion?

Answer 2

Temperature, concentration gradient, membrane surface area

Question 3

How does membrane surface area affect diffusion?

Answer 3

The larger the surface area of the membrane that a substance is diffusing through (e.g. the membrane around a cell), the faster the rate of diffusion.

Question 4

How does temperature affect diffusion?

Answer 4

The higher the temperature, the faster the rate of diffusion.

Question 5

How does concentration gradient affect diffusion?

Answer 5

The bigger the difference in concentration between two areas, the greater the concentration gradient and the faster the rate of diffusion.

Question 6

What is osmosis?

Answer 6

Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high concentration of water) to a concentrated solution (low concentration of water).

Question 7

What is an independent variable?

Answer 7

A variable which is controlled and is changed in the experiment

Question 8

How do you calculate the percentage change in mass?

Answer 8

(final mass - initial mass)÷ initial mass x 100

Question 9

What are the three main forms of transport in cells?

Answer 9

Osmosis, diffusion, active transport

Question 10

What is active transport?

Answer 10

Active transport is the net movement of particles against a concentration gradient.
Energy is therefore required.

Question 11

What is a dependant variable?

Answer 11

A dependent variable is what we measure in an experiment.

Question 12

What a waste product is removed during diffusion at the lungs?

Answer 12

CO2

Question 13

What are stem cells

Answer 13

Cells that have not yet undergone differentiation (unspecialised cells)

Question 14

What happens when a cells differentiates

Answer 14

It becomes specialised

Question 15

Give 3 examples of where stem cells are found in the body

Answer 15

Bone marrow
Muscle
Heart

Question 16

Where does cell division in plants occur

Answer 16

In meristems

Question 17

How do cells become differentiated in a meristem

Answer 17

As the shoot grows new cells are being produced continuously near the tip. These will eventually become differentiated and enlarge to form a vacuole

Question 18

Why are stems cells useful to us

Answer 18

They have the potential to be transplanted into patients with a disease by replacing cells have been damaged or destroyed

Question 19

What stem cells can be used for stem cell transplants

Answer 19

Embryonic stem cells (can differentiate into a wide range of cell types)
Adult stem cells ( can differentiate into a narrow range of cell types)

Question 20

What are the ethical issues associated with embryonic stem cells used in medicine

Answer 20

At what stage of its development should an embryo be regarded as a person
Fear that embryos will come to be viewed as a commodity

Question 21

What are the three main types of neurones

Answer 21

Sensory
Motor
Relay

Question 22

Where do 2 neurones meet

Answer 22

A synapse

Question 23

How does an electrical signal travel across a synapse

Answer 23

1. Electrical impulse travels along first axon
2. Triggers the nerve ending of a neurone to release chemical messengers (neurotransmitters)
3. These chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the next neurone
4. They only bind to the specific neurotransmitters released from the first neurone
5. Stimulates the second neurone to transmit the electrical impulse

Question 24

What is the CNS

Answer 24

Central nervous system
(Brain & spinal cord)

Question 25

What are effectors

Answer 25

Include muscles and glands Produce a specific response to a detected stimulus

Question 26

Flow diagrams to show how information flows from receptors to effectors

Answer 26

Stimulus —> receptor —> coordinator —> effector —> response

Question 27

Order of reflex arc

Answer 27

Stimulus —> receptor —> sensory neurone —> relay neurone —> motor neurone —> effector —> response

Question 28

What does the reflex arc do in order to increase the speed of a reaction

Answer 28

Pathway of reflex arc does not initially go to the brain

Question 29

Where is the medulla oblongata found

Answer 29

Top of the spinal cord

Question 30

Where is the cerebellum found

Answer 30

Base of brain at the back

Question 31

Where is the cerebrum found

Answer 31

Front of brain

Question 32

Describe the function of the medulla oblongata

Answer 32

Controls the unconscious activities such as heart rate and breathing rate

Question 33

Describe the function of the cerebellum

Answer 33

Controls balance, coordination of movement and muscular activity

Question 34

Describe the function of the cerebrum

Answer 34

Outer layer is split into two hemispheres which make up cerebral cortex Controls most of our senses, intelligence, personality, conscious thoughts, language and verbal memory

Question 35

How can CT and PET scanners help overcome issues investigating functions of the brain

Answer 35

CT- series of x-rays from different angles are processed and allow doctors to see inside the brain PET- detect gamma rays that radiate from a tracer injected by the patient. The tracer attaches to a tumour and so the pet scanner is often used to detect cancer

Question 36

What is the function of the cornea

Answer 36

Refracts light as it enters the eye

Question 37

What is the role of the lens

Answer 37

Further refracts light and focuses it onto the retina

Question 38

What is the role of the iris

Answer 38

Controls how much light enters the pupil

Question 39

What is the role of the retina

Answer 39

Contains light receptors

Question 40

What are the roles of the rods and cones in the retina

Answer 40

Rods are used for seeing in dim light as they are more sensitive to light than the cones Cone cells produce colour vision

Question 41

What does the lens do to focus on a near object

Answer 41

The lens becomes thicker which allows the light rays to retract more strongly

Question 42

What does the lens do to focus on a distant object

Answer 42

The lens is pulled thin which allows the light rays to refract slightly

Question 43

How can short and long sightedness be corrected

Answer 43

Spectacle lenses or contact lenses which refract the light so the rays focus on the retina

Question 44

What is the difference between long and short sighted people

Answer 44

Short sighted - see nearby objects Long sighted - can see objects for away

Question 45

What is cataract

Answer 45

A cloudiness in the lens caused by a build up of protein

Question 46

How can cataracts be corrected

Answer 46

Removing the lens and replacing it with a plastic lens

Question 47

Compare and contrast active transport and diffusion

Answer 47

Diffusion is net movement of particles from high to low concentration Diffusion does not require energy Diffusion occurs down a concentration gradient (Active transport is everything opposite)

Question 48

Give an example of active transport

Answer 48

Plants use it to absorb nitrates from soil

Question 49

Give an example of diffusion

Answer 49

Oxygen diffuses from alveoli into the blood in the lungs

Question 50

What do relay neurones do

Answer 50

Carry electrical signals around the CNS

Question 51

What do motor neurones do

Answer 51

Carry electrical signals away from the CNS to effectors which are muscles or glands

Question 52

What is the purpose of the myelin sheath

Answer 52

Insulated the axon and speeds up the electrical signals

Question 53

How do painkillers stop someone feeling pain in terms of the CNS

Answer 53

Prevent neurotransmitters from binding to the receptors in the next neurone Causes no electrical impulse to be triggered Signal is not received by the CNS (person doesn’t feel pain)