Biology unit 14

Question 1

Neurons

Answer 1

A nerve is a bundle of neurons
Electrical impulses are sent through nerves to quickly send signals around our body
Used for rapidly coordinating or regulating the bodies functions (heart rate increases, liver release glucose and bladder relaxes.

Question 2

Central nervous system

Answer 2

Consist of brain and spinal cord

Question 3

Peripheral nervous system

Answer 3

Consist of all other nerves in the body

Question 4

neuron structure

Answer 4

• dendrites receive signals from surrounding neurons they are branched to allow connections with many neurons
• the axon is a long structure off the cell body that electrical signals can be rapidly sent through. It’s long length allows for signals to be sent rapidly.

Question 5

neuron structure part two

Answer 5

• the axon terminal is where the signal is passed to the next neuron over the synapse.
• nerve signals are always sent one way

Question 6

How are nerve signal sent? - Reflex responses

Answer 6

1) stimulus e.g pain,smell,taste,visual,chemical is is received by a receptor
2) sensory neurons past signals back to the relay neuron in the CNS
3) the relay neuron sends this signal onto the motor neuron
4) the motor neuron sent the signal to effector organ usually a muscle or gland which is dense stimulated to respond
5) reflexes allow us to respond to stimuli extremely fast without conscious thought - signal doesn’t need to be interpreted by brain

Question 7

Types of neurons

Answer 7

Sensory neurons have their cell body half way down the axon
* Relay neurons have a short axon (as they are not sending signals long distances)
* Motor neurons have the cell body at the end with the dendrites

Question 8

Optic nerve

Answer 8

Sends nerve signals from the rod and cones cells in the retina to the brain

Question 9

Retina

Answer 9

Is where light is focused in the eye. It contains light sensitive rod and cone
receptor cells

Question 10

Iris

Answer 10

Is the coloured part of the eye which affects the size of the pupil.

Question 11

Lens

Answer 11

Is able to change shape to focus light onto the retina.

Question 12

Pupil

Answer 12

Is the opening in the eye which allows light to enter.

Question 13

Suspensory ligaments

Answer 13

Attaches the lens to the ciliary muscles

Question 13

Cornea

Answer 13

Is the curved part of the eye which refracts light as it enters.

Question 14

Ciliary muscles

Answer 14

They contract or relax to make the suspensory ligaments go slack or tight
respectively, therefore changing the shape of the lens

Question 15

Radial muscles

Answer 15

Contract in low lights so the pupil will appear larger

Question 16

Circular muscles

Answer 16

Contract in bright light, so the pupil will appear smaller

Question 17

Rod cells

Answer 17

Detects differences in light intensity, does not detect colour, use extensively and dim light
Information is carried by sensory neurons to the occipital lobe

Question 18

Cone cells

Answer 18

Detect differences in colour, different cones detect red/blue/green
Information is carried by sensory neurons to the occipital lobe

Question 19

The fovea

Answer 19

In the eye, a tiny pit located in the
retina that provides the clearest vision of all. The eye lens will focus light on to the fovea.
* No rods, only cones

Question 20

Colour

Answer 20

Red, green and blue cones work together
to allow us to perceive a range of colours

Question 21

What is a hormone

Answer 21

Chemical substance produced by a gland and carried by the blood which alters the activity of one or more specific target organs

Question 22

Nerves and hormones

Answer 22

Nerves: sends signals fast through neurons
Effect is short term

Hormones: sends signals slowly through bloodstream

Question 23

Hormones that control blood glucose levels - adrenaline

Answer 23

Adrenaline- secreted from adrenal gland causes liver to breakdown glycogen and release glucose into the bloodstream

Question 24

Hormone that control blood glucose levels - glucagon

Answer 24

Secreted from pancreas. Causes the liver to break down glycogen into glucose and release it into the bloodstream. Used when blood sugar levels are low but not death situation

Question 25

Hormones that control blood glucose levels - insulin

Answer 25

Secreted from the pancreas. Causes the liver to absorb glucose in to the bloodstream and convert it to glycogen for later use. Used when our blood sugar levels are high

Question 26

What is homeostasis

Answer 26

The maintenance of a constant internal
environment
* Homeostasis always tries to keep a variable
in our body at a set point using negative feedback
* If a variable changes from the set po’int it will be detected by a receptor, transmitted by nerves and an effector will be activated to return the variable to its set point

Question 27

Type 1 diabetes

Answer 27

Type one diabetes is a disorder in which the pancreas failed to produce sufficient insulin to control blood glucose levels
Type one diabetes are normally treated with insulin injections - uncontrolled high blood glucose levels

Question 28

Type two diabetes

Answer 28

The body cells no longer response to insulin produced by the pancreas- cells are resistant and don’t responds as well as they should - uncontrolled high blood glucose levels
Carbohydrate control diet and exercise regime are common treatments for type two diabetes

Question 29

What is a tropism

Answer 29

• it’s the growth response of an organism towards or away from a stimulus
  Phototropism - growing towards or away from light
  Gravitropism- growing towards or away from gravity

Question 30

Auxin

Answer 30

is a growth regulating hormone. It makes plant shoot cells elongate. Auxin. Loosen the cell wall and stimulates cell elongation. Auxin is produced in the shoot tip and moves away from light.

Question 31

Gravitropism

Answer 31

Auxin is also produced at root tips and has the exact opposite effect on
root cells. It inhibits cell elongation
Auxin also sinks to the bottom side of roots
This inhibits cell elongation on the bottom side of the root, causing the
root to grow down