Organisms respond to changes in their internal and external environments

Question 1

What is a taxes

Answer 1

Movement of a motile organism in response to a stimulus (usually an environmental change)

Question 2

What is a positive taxis

Answer 2

organism moves towards a stimulus (usually favourable)

Question 3

What is a negative taxis

Answer 3

organism moves away from a stimulus (usually unfavourable)

Question 4

What is the purpose of a taxis

Answer 4

Increases chances of the organism’s’ survival in all cases

Question 5

What is kineses

Answer 5

A form of response in which the motile organism does not move towards/away from a stimulus, but instead shows a random, non-directional response (eg. the organism changes the speed at which it is moving and the rate at which it changes direction in response to a stimulus)

Question 6

What is a tropism

Answer 6

The growth of plants in response to a directional stimulus
e.g. The plant grows towards (positive response) or away (negative response) from a stimulus

Question 7

What is the kinesis for water

Answer 7

hydrotropism (positive in roots)

Question 8

What is the kinesis for gravity

Answer 8

gravitropism (positive in roots, negative in shoots)

Question 9

What is the kinesis for light

Answer 9

phototropism (positive in shoots, negative in roots)

Question 10

What is a reflex arc

Answer 10

a completely involuntary and instantaneous movement in response to a stimuli

Question 11

Describe the structure of a myelinated motor neurone

Answer 11

• dentrites/dendrones
• cell body
• nucleus
• axon
• myelinated sheath
• schwann cells
• nodes of ranvier
• axon terminals

Question 12

Definition of the nervous system

Answer 12

a system that uses nerves to pass electrical impulses to communicate

Question 13

Definition of the hormonal system

Answer 13

a system that produces chemicals that are transported in the blood to their target cells (via receptors) to communicate

Question 14

Differences between the nervous and hormonal systems

Answer 14

NERVOUS SYSTEM
- short-lived
- transmission by neurones
- very rapid acting
- usually temporary and reversible
- muscles
HORMONAL SYSTEM
- long lasting
- transmission by blood stream
- relatively slow
- may be permanent and irreversible
- glands

Question 15

How does phototropism work in plants

Answer 15

SHOOTS
IAA moves to the shaded side of stem, causes elongation of cells here, so the plant will bend towards the unidirectional light
this is positive phototropism
ROOTS
IAA moves to the shaded side of the stem, but inhibits the elongation of cells, so the roots bend away from the unidirectional light
this is negative phototropism

Question 16

How does gravitropism work in plants

Answer 16

IAA moves to the underside of shoots and roots and either inhibits or stimulates growth, causing the plant to bend against/with gravity
In shoots, there is negative gravitropism and in roots there is positive gravitropism

Question 17

What is the nervous system made up of

Answer 17

receptors
sensory neurones
CNS and relay/intermediate neurone
motor neurone
effectors

Question 18

What is smooth muscle

Answer 18

muscle that contracts without conscious control, found within walls of internal organs

Question 19

What is cardiac muscle

Answer 19

muscle that contracts without conscious control but only found in the heart

Question 20

What is skeletal muscle

Answer 20

muscle that we use to move limbs and ourselves

Question 21

What are antagonistic pairs of muscles

Answer 21

Muscles that move a bone together, where one contracts (agonist) and the other relaxes (antagonist).
Examples are our triceps and biceps