Sensitivity And Coordination

Question 1

Why do organisms need sensory and coordination abilities?

Answer 1

To avoid danger, find resources and time their reproduction with favourable seasons.

Question 2

Why do grasshoppers have ears on each side its abdomen?

Answer 2

To quicken its reflex to jump.

Question 3

Define the term ‘stimuli’ with an example.

Answer 3

Stimuli are things which cause responses in organisms. Example, the smell of food can be a stimuli for more production of saliva in you mouth.

Question 4

What is the difference between the endocrine system and the nervous system?

Answer 4

The endocrine system uses chemical messengers called hormones to coordinate slow and extended responses such as growth and metabolic rate whereas the nervous system communicates by rapid electrical impulses for immediate sensory and coordination needs as a vision and movement.

Question 5

3 differences between endocrine and nervous system.

Answer 5

-endocrine system is slow whereas nervous system is quick.
- endocrine system have long term responses whereas the nervous system have short term responses.
- endocrine system consist of glands and hormones whereas the nervous system consists of nerve cells, neuron and fibres.

Question 6

State 3 roles of hormones in plants

Answer 6

• Controlling tropisms
• for growth
• for reproduction

Question 7

True or false: Hormones control the fruiting- ripening, flowering and falling of leaves in seasonal plants.

Answer 7

True.

Question 8

What would happen if there were no hormones in plants?

Answer 8

The roots would grow randomly, with some of it growing directly towards the sky. Some branches would be flowering and fruiting while others would be dropping leaves. And angiosperms of the same species which flower at different times of the year, would have low chances of pollination.

Question 9

How can the sensitivity of a plant tissue to a given hormone be altered?

Answer 9

• By changing the hormone concentration in the target tissue.
  -By altering the receptor sensitivity to that hormone in the target tissue.

Question 10

State 3 roles of the hormone auxin.

Answer 10

• responsible for cell division and growth in cell size.
• prevents abscission
  -Involved in apical dominance and various tropisms.

Question 11

Example of an auxin is?

Answer 11

IAA, indole acetic acid

Question 11

Example of an auxin is?

Answer 11

IAA, indole acetic acid

Question 12

State 3 roles of the hormone cytokinin

Answer 12

• promotes cell division in plant roots and shoots.
  -promotes growth of buds
  -delays senescence and activate dormant buds.

Question 13

Example of the hormone cytokinin

Answer 13

Zeatin

Question 14

What are 3 roles of the hormone ethylene.

Answer 14

• responsible for senescence process
• promotes the ripening of the fruit
• affects plant functions such as abscission of leaves, seed germination and drooping of leaves.

Question 15

State the 2 roles of abscisic acid (ABA0)

Answer 15

• maintains dormancy in seeds and buds
• stimulates the closing of stomata.

Question 16

state 3 roles of the hormone gibberellins

Answer 16

• responsible for cell division and growth in cell size
• causes elongation of stems
• stimulate pollen tube growth

Question 17

What is the function of receptors?

Answer 17

To sense stimuli.

Question 18

What is the function for the communication system?

Answer 18

To carry the message between the receptors and effectors.

Question 19

What is the function of effectors?

Answer 19

Are muscles and glands that act out the response.

Question 20

Describe asymmetrical animals and give an example.

Answer 20

Are animals with no body symmetry for example, sponges.

Question 21

Describe everything about radially symmetrical animals and give an example.

Answer 21

Are animals that can be divided into similar halves by passing a plane through the central axis. They have the ability to sense from all directions. Mostly posses simple nerve network with no centralized sensing or .processing. Examples are cnidarians ( hydra and jellyfish) and echinoderm (sea urchin, star fish) as adults.

Question 22

Describe everything about bilaterally symmetrical animals.

Answer 22

Are animals that can be divided into two matching halves by passing a plane through the central axis, creating left and right sides.

Question 23

Which part is favoured by natural selection in bilaterally symmetrical animals, and why?

Answer 23

The head end, because they come first in contact with food and danger. So the head end is favoured by natural selection for sensory ability centralized in the head.

Question 24

What did nerve centralization result in?

Answer 24

It resulted in the evolution of the increasingly complex animal nervous systems.

Question 25

What are some examples of bilaterally symmetrical animals?

Answer 25

Flatworms, arthropods, molluscs , annelids, vertebrates.

Question 26

Identify the nerve system in cnidarians and how they work?

Answer 26

Nerve net system. They have touch receptors in their skin, when anything stimulates these receptors, a reflex action begins. The stimulated sensory receptors signal poison cells to sting the potential prey and tell the tentacles to pull the prey into the mouth.

Question 27

Comment on the sensory and coordination abilities of annelids compared to cnidarians.

Answer 27

They have complex sensory and coordination abilities compared to cnidarians.

Question 28

What is meant by ‘ganglia’?

Answer 28

They are neurons concentrated in clusters. They are connected to each other in chain-like fashion by two nerve cords.

Question 29

What are nerve cords?

Answer 29

A bundle of neurons that run the length of the organism.

Question 30

What is the function of the ganglia at the anterior end? (cerebral ganglia)

Answer 30

It functions like a ‘mini brain’. It processes stimuli’s and work with the nerve cords to coordinate movements.

Question 31

What are some factors that limit annelids sensory abilities?

Answer 31

Light intensity (dehydration), and touch and chemical sensitivity ( allows it to search for food and avoid danger).

Question 32

Describe how different classes within the molluscs phylum differ in sensitivity and coordination?

Answer 32

Bivalves (kai) and snails are slow moving organisms, so they have a simple nerve network, controlled by brain-like neuron concentration whereas in fast moving molluscs like squid and octopus, they have a complex brain that allows them to respond very quickly to food and danger.

Question 33

Which phylum has the most developed nervous system?

Answer 33

Arthropods, especially the ones that can fly.

Question 34

Describe the nervous system of arthropods.

Answer 34

They all have dorsal brain and a ventral nerve cord with ganglia from which lateral nerves extend in each segment. These miniature brain and nerve cord often exert as much control over the coordination as the real brain in the head.

Question 35

What kind of eyes do insects and arthropods posses?

Answer 35

Compound eyes, which help them detect quick movements.

Question 36

What are the function of antennae in insects?

Answer 36

They are receptors of touch, smell, sound and taste.

Question 37

What are 3 major developments that nervous system of vertebrates rest on?

Answer 37

1.Well developed sense organs.
2. Complex motor structures
3. Centralized processing and control centre.

Question 38

Why do fast moving animals need powerful sensory organs?

Answer 38

So that they do not run into things and to find enough food to support their high energy demands.

Question 38

Why do fast moving animals need powerful sensory organs? Also give an example.

Answer 38

So that they do not run into things and to find enough food to support their high energy demands. for example, birds have sharp eyesight to avoid flying into things

Question 39

How do mongoose keep track of their prey?

Answer 39

They have a excellent sense of smell of keep track of their prey.

Question 40

What controls the muscular system of a vertebrate?

Answer 40

The brain and spinal cord.

Question 41

What do hormones from the endocrine systems do?

Answer 41

They manage metabolic rates, emotions, growth and other processes requiring coordination.

Question 42

What kind of nervous system do vertebrates have and what do they consist of?

Answer 42

Central nervous system (CNS), consisting of a brain and a spinal cord.

Question 43

What part of the brain is responsible for thinking and what does the rest of it do?

Answer 43

Cerebrum is responsible for thinking and the rest of the brain is devoted to reflex actions such as heartbeats, breathing and muscles coordination.

Question 44

Which class has the largest cerebrum?

Answer 44

Mammals.

Question 45

What does a large cerebrum mean and what is the cerebrums cover called?

Answer 45

Large cerebrum means greater intelligence. The cerebrum cover is known as the cerebral cortex.

Question 46

In mammals, what has the cerebral cortex evolved into?

Answer 46

It has evolved into a complex information processing centre in mammals.