Animal Diversity- FUNCTIONS

Question 1

Characteristics of Asymmetry (3)

Answer 1

1. irregular - no symmetry, therefore it is unicellular
2. sessile
3. no need to sense environment for food ( food taken from water flowing)

Question 2

Characteristics of Radial symmetry (3)

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Answer 2

1. divided around central axis
2. sessile
3. can sense stimuli from all directions + move in all directions ( random movement due to no cephalisation)

Question 3

Characteristics of Bilateral symmetry (4)

Answer 3

1. divide either side of central axis
2. posterior and anterior end
3. motile
4. cephalised- pray detection - co ordinated movement

Question 4

Explain cephalisation?

Answer 4

head with anterior end which contains a concentration of nerve cells forming a brain. this allows to interpret stimuli and respond accordingly.

Question 5

what symmetry do you find cephalised animals?

Answer 5

bilateral symmetry

Question 6

why do cephalised animals enter environment head first.

Answer 6

anterior end contain sense organs in head are near ‘brain’.

Question 7

explain the 3 embryonic germ layers?

Answer 7

ectoderm- outer - forms skin (controls body muscle)
endoderm- inner- lines gut (controls gut muscles)
mesoderm- middle- gives rise to internal organs

Question 8

what type of germ layered animals have coelom?

Answer 8

triploblastic animals

Question 9

What does the coelom allow for in terms of the germ layers?

Answer 9

allows separation of gut from body wall meaning endoderm (gut muscles) can move independently and contract to aid digestions without affecting the rest of the body.

Question 10

advantages of coelom?(4)

Answer 10

• coelom fluid can allow for hydrostatic skeleton
• body fluid can redistribute- aid locomotion
• mass off tissue does not restrict organs to grow larger and move freely
• materials can diffuse faster through coelom fluid in body cells

Question 11

what is a coelom filled with blood called?

Answer 11

heamoceal

Question 12

what is an animal with no coelom called?

Answer 12

acoelomate

Question 13

disadvantages of blind gut? (4)

Answer 13

• cannot ingest and egest at the same time
• ingest, digestion egestion are not systematic
• NOT EFFICIENT- mixing of digested and undigested food
• digested food can also be expelled during egestion

Question 14

Advantages of. through gut? (3)

Answer 14

• allows for specialisation = mouth ingest, stomach+ intestines digest and anus egest
• all 3 systematic
• no mixing of indigested and digested food

Question 15

explain an open blood system?

Answer 15

blood flows through blood vessels- opens into body cavity (heamocoel)- contacts with tissues and organs- diffusion of gasses- returns to open blood vessels- to heart and circulates in same direction.

Question 16

explain an closed blood system?

Answer 16

heart pumps blood- through system of tubes (arteries, capiliries and veins)- blood out the vessels and into cells with no direct contact- diffusion of gasses occur and blood goes back to heart

Question 17

advantages of closed blood system?(3)

Answer 17

• faster circulation
• increase in size of organism
• more activity

Question 18

Explain hydrostatic skeleton?

Answer 18

Body supported by a fluid filled structure such as coelom or blood in a heamoceal

Question 19

Explain exoskeleton? (2)

Answer 19

• Hard waxy coating on outside of body that protects internal organs
• frame work for support and muscle attachment

Question 20

Explain endoskeleton? (2)

Answer 20

• framework within body that protects organs

- muscle brace to pull on