1.2

Question 1

When did prokaryotes originate

Answer 1

around 3.5 billion years ago

Question 2

Structure of prokaryotic cells

Answer 2

Cytoplasm 
70s ribosomes 
Plasma membrane 
Pili 
Flagella 
Plasmids
Nucleioid region

Question 3

What is the role of the cell wall

Answer 3

to enclose the cell, protect and maintain shape

prevents bursting in hypotonic media

Question 4

What is the whole of the plasma membrane

Answer 4

surrounds the cell and controls the movements of substances in and out of the cell

Question 5

What is the role of the cytoplasm

Answer 5

medium that fills the cell

site of metabolic reactions

Question 6

What is the role of the flagella

Answer 6

responsible for the locomotion of the organism

their whip like movement propels the cell along

Question 7

What is the role of the Pili

Answer 7

protein filaments that help with cell adhesion and the transference of DNA

Question 8

What is the role of the 70s ribosomes

Answer 8

the site of protein synthesis

Question 9

What is the role of the nuclide region

Answer 9

controls all the activities of the cell and the reproduction of the organism

Question 10

What is the role of plasmids

Answer 10

Small circles of DNA that carry a few genes often these genes give the cell antibiotic resistance and are used in creating genetically modified bacteria

Question 11

What is the difference between 70 and 80s ribosomes

Answer 11

70s are smaller than 80s and are found in prokaryote cells

Question 12

How do prokaryotes reproduce

Answer 12

by binary fission to produce genetically identical cells

Question 13

What are the steps of binary fission

Answer 13

(asexual process)

• the chromosome is replicated semi-conservatively, beginning at the point of origin
• two copies of the DNA move to opposite ends of the cell
• the cell elongates
• the plasma membrane grows inward and pinches off to form two separate genetically identical cells

Question 14

What is the DNA not associated with in prokaryotes

Answer 14

it is not associated with histones

Question 14

What is the DNA not associated with in prokaryotes

Answer 14

it is not associated with histones

Question 15

What is compartmentalisation

Answer 15

refers to the formation of compartments within the cell by membrane bound organelles

Question 16

What are advantages of compartmentalisation

Answer 16

• greater efficiency of metabolism as enzymes and substrates are enclosed, much more concentration
• internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes
• isolation of toxic or damaging substances away from the cytoplasm, such as the storage of hydrolytic enzymes in lysosomes
• flexibility of changing the numbers and position of organelles within the cell based on the cell’s requirements

Question 17

Cellular structures of eukaryotic cells

Answer 17

Plasma membrane 
Cytoplasm 
80s ribosomes
rough endoplasmic reticulum 
smooth endoplasmic reticulum 
goggles apparatus
vesicles
lysosomes (not in plant cells) 
mitochondria 
centrioles (not in plants) 
nucleus 
nucleolus
vacuoles 
chloroplast (not in animal cells)
Cell wall (not in animal cells)

Question 18

Role of plasma membrane

Answer 18

controls the movement of substances in and out of the cell

Question 19

Role of cytoplasm

Answer 19

medium that fills the cell

where are the enzymatic reactions occur

Question 20

role of mitochondria

Answer 20

site for cellular respiration, ATP is generated

Question 21

role of 80s ribosomes

Answer 21

site of protein synthesis

Question 22

role of nucleus

Answer 22

controls all the activities of the cell as well as the reproduction of unicellular organism

Question 23

role of the nucleolus

Answer 23

part of the nucleus which is involved in the production of ribosomes

Question 24

role of the SER

Answer 24

stores and produces lipids

Question 25

role of RER

Answer 25

transports protein to the Golgi apparatus usually for use outside of the cell

Question 26

role of the Golgi apparatus

Answer 26

processes and packages proteins released in Golgi vesicles

Question 27

role of vesicle

Answer 27

small sac that transports and releases substances produced by the cell by fusing with the membrane

Question 28

role of lysosomes

Answer 28

contains hydrolytic enzymes and plays important role in the destruction of microbes engulfed by white blood cells

Question 29

role of centrioles

Answer 29

role in the process of nuclear division, helps establish microtubules

Question 30

role of vacuole

Answer 30

helps in the osmotic balance of the cell and the storage of substances , can at times have similar hydrolytic functions to lysosomes

Question 31

role of cell wall

Answer 31

protects the cell, maintains shape and prevents it from bursting in hypotonic media

Question 32

role of chloroplast

Answer 32

double membrane bound organelles, contain pigments and are responsible for photosynthesis

Question 33

what can replace the role of lysosomes in plants

Answer 33

vacuoles

Question 34

what is a free vesicle (protein)

Answer 34

vesicles that stay in the cell

Question 35

what is microscope resolution

Answer 35

the shortest distance between two separate points in a microscopic's field of view that can still be distinguished as distinct objects

Question 36

what is an advantage of using a light microscope over an electron microscope

Answer 36

allows us to observe living specimen

Question 37

what organelle cannot be viewed with a standard light microscope

Answer 37

80s ribosomes

Question 38

Draw a labeled diagram to show the ultrastructure of Escherichia coli. 6 marks

Answer 38

``` cell wall slime capsule cell membrane cytoplasm nucleoid flagellum pilli plasmids 70s ribosomes ```

Question 39

State one function of each of the following organelles: lysosome, Golgi apparatus, rough endoplasmic reticulum, nucleus, mitochondrion. 5 marks

Answer 39

lysosome - contains hydrolytic enzymes to break down harmful substances Golgi apparatus I the processing and packaging of proteins RER - transports proteins and the site of synthesis nucleus - controls activity, and contains genetic material mitochondria - site of cellular respiration ATP generated

Question 40

Distinguish between the structure of plant and animal cells. 6 marks

Answer 40

Plants: ``` store starch chloroplast, animals do not central vacuole, animals do not cell wall, animals do not fixed more regular shape ``` Animals: store glycogen centrioles, plants to not more rounded shape

Question 41

what is the cell wall made up of in prokaryotes

Answer 41

peptidoglycan

Question 42

how does the flagella differ in eukaryotes and in prokaryotes

Answer 42

eukaryotes flagella is flexible and it is solid in prokaryotes