unit 1

The figure showed is an electron micrograph showing the bacteria, Vibrio cholerae.

(a) (i) Bacteria are prokaryotes.

State two distinguishing features of all prokaryotes.

1 .............................................................................................................................

2 .............................................................................................................................

Answer explanation

prokaryotes are

unicellular ;

No nucleus

Has no (membrane-bound) organelles

Has (peptidoglycan / murein) cell wall ;

reproduce by binary fission ;

Has 70S, ribosomes ;

Has plasmids ;

(ii) The bacteria shown in Fig. 2.1 each have a flagellum.

Suggest the function of the flagellum in bacteria.

Identify the species of mollusc labeled A to E.

a

b

c

d

e

B

E

A

D

C

Identify the species labeled with letters A to G.

a

b

c

d

e

f

G

E

F

A

D

C

(b) State two features that are shown by all molluscs.

1 ................................................................................................................................................

2 ................................................................................................................................................

Name the vertebrate group that contains lizards.​ ​ ​ (a)   ​

• Reptile
• mammals
• Amphibians

Use the key to identify each species. Write the letter of each species (A to G) in the

correct box beside the key. One has been done for you.

a

b

c

d

e

f

C

B

E

G

F

A

Myriapods are a group of arthropods that are commonly found in soil habitats in many parts of the

world. Many myriapods are very small and not easy to identify.

(a) State three features of all myriapods that are visible in Fig. 6.1.

1 ...............................................................................................................................................

...................................................................................................................................................

2 ...............................................................................................................................................

...................................................................................................................................................

3 ...............................................................................................................................................

..............................................................................................................................................

Myriapods are a group of arthropods that are commonly found in soil habitats in many parts of the

world. Many myriapods are very small and not easy to identify.

(b) Describe three features of myriapods that could be used to make a dichotomous key to

distinguish between the four species in Fig. 6.1.

1 ...............................................................................................................................................

...................................................................................................................................................

2 ...............................................................................................................................................

...................................................................................................................................................

3 ...............................................................................................................................................

..............................................................................................................................................

Answer explanation

These are the key in MS should be used

length of antennae ;

number of sections on antennae ;

presence / absence, of tail pieces / AW ;

length of tail pieces ;

length of legs ;

number of leg joints ;

total number of legs ;

position of legs on body ;

number of legs per segment ;

size / shape of segments ;

number of body segments ;

length of body ;

head shape ;

presence / absence ‘spots / markings’ ;

Table 1.1 shows some features of the five groups of vertebrates.

Complete Table 1.1 to compare the five groups of vertebrates using a tick (√) to

indicate if the group shows the feature, or a cross (×) if not.

The first row has been completed for you.

Groups:

(a) scally skin

,

(b) external ear pinna

,

(c) glands

• bony fish

• mammal

• mammals

• reptiles

Answer explanation