Part 6 - Responses To Stimuli

Question 1

What is stimuli?

Answer 1

Something that elicits a response

Something that produces a reaction in a living organism

Something that a living organism reacts to

Question 2

Can you distinguish between a heterotroph and an autotroph?

Answer 2

A heterotroph gets its food from other organic sources whereas an autotroph makes its own food

Question 3

Define the term chemotaxis?

Answer 3

Chemo - chemical
Taxis- movement

Movement of organisms due to chemical stimulation

Question 4

What are chemoattractants?

Answer 4

They result in an organism moving towards the chemical

Question 5

What are chemorepellents ?

Answer 5

They result in the organism moving away

Question 6

What is flagella (flagellum) and what is its role?

Answer 6

It is a whip like structure that protrudes from the membrane of bacteria

It’s primary role is to help the bacteria move but they can also function as sensory organelles being sensible to chemicals and temperatures outside of the cell

Question 7

How do amoebae and bacterial know to move towards a chemoattractant?

Answer 7

They must first
Recognise it

Then respond to the stimuli

Question 8

Where does recognition from a single celled organism of a chemical occur?

Answer 8

On the outside of the cell membrane and cell surface receptors

Question 9

What are cell surface receptors?

Answer 9

They are biological complexes found in the cell membrane that allow recognition of a specific extracellular chemicals

Question 10

What is the transference of the message from outside of a cell to the inside known as?

Answer 10

Signal transduction

Question 11

What is a ligand?

Answer 11

It is a small compound that attaches to one type of cell surface receptor and induces a change in the shape of the receptor
This results in the message being transferred into the cell

Question 12

What is tropism?

Answer 12

It is a plants response to stimuli

Question 13

What external stimuli will green plants need to grow towards and why?

Answer 13

Plants will need to grow towards the sun to allow photosynthesis to occur. Plants may also grow towards water

Question 14

What is the term given for when plants grow towards light?

Answer 14

Phototropism

Question 15

What is gravity?

Answer 15

The force that attracts the body to the Earth

Question 16

What is gravitropism?

Answer 16

It is a phenomenon where plants grow up and defy gravity

Question 17

Are plants stems

Positively phototropic or negatively phototropic?

Answer 17

Positively phototropic

Question 18

Are plant roots

Positively phototropic or negatively phototropic?

Answer 18

Negatively phototropic

Question 19

Are any stems

Negatively gravitropic
Or positively gravitropic

Answer 19

Negatively gravitropic

Question 20

Are plant roots

Negatively gravitropic
Positively gravitropic

Answer 20

Positively gravitropic

Question 21

Why do you think it is that roots are gravitropic?

Answer 21

Roots growing down and away from light are more likely to find soil, water and minerals they need

Question 22

Why do you think plant stems are phototropic?

Answer 22

They need to grow towards the light to be able to expose their leaves so that photosynthesis can occur

Question 23

What are the hormone/chemical messengers in plants called?

Answer 23

Auxins (meaning to grow)

Question 24

What observations can you make when seedlings grow?

Answer 24

They grow towards the light source (positive phototropism)
The seedlings change their direction of growth towards the light source
They do not grow at the same rate

Question 25

What 5 senses do animals have?

Answer 25

5
Touch
Taste
Smell
Sight 
Hearing

Question 26

What do senses allow animals to receive?

Answer 26

Information about their external surroundings

Question 27

What external change can be detected by animals ?

Answer 27

Animals can detect visual and audible stimuli, as well as temperature, day length, gravity and the earths magnetic field. They can also detect chemical changes.

Question 28

How does an adder sense without the ability to hear?

Answer 28

The adder senses vibrations in the ground and uses its forked tongue to detect chemical change in the air

Question 29

What is a nervous system?

Answer 29

It is the sensory and control apparatus of the body

It responds to external stimuli

Question 30

What is the job of the nervous system?

Answer 30

To take information from the external environment
Compute the information
And respond appropriately

Question 31

What is the a nerve cell called?

Answer 31

Neuron

Question 32

What method of transmission does the nervous system use to transmit messages ?

Answer 32

Electrical and chemical

Question 33

What is the gap between each neuron called where electrical impulses jump from one cell to another?

Answer 33

Synapses

Question 34

What method of transmission does a synapses use in a nerve pathway?

Answer 34

A chemical transportation of the message

Question 35

What method of signal transmission is used within the neuron and what system is used to transmit messages between neurons?

Answer 35

Impulses are transmitted as electrical messages within a neuron and as chemical messages between neurons