Observation

The candidates that performed well in this question were able to identify the organisms in the diagrams correctly.

Many candidates lost marks for wrong identification of labelled parts, wrong spelling of technical terms and ignorance about the economic importance of bacteria.

The expected answers are:

 

4  (a) (i) Identification
C- Volvox
D- Bacterium
E- Spirogyra

 

(ii)    Label of parts             
I-Flagellum                  V-Cytoplasm
II-Protoplasmic/Cytoplasmic strand  VI-Chromosome/genetic material
III-Cell                      VII-Cell wall
IV-Flagella                   VIII-Chloroplast        

NOTE: Spelling must be correct to score

(b) (i)  Forms in which they exist
C- Colony
D- Singly/chains/cluster/twos
E- Filament

 

(ii)  Effect of C and E living separately
- Volvox cell/C will soon die; because the cells are specialized/there is division of labour/ so each individual cell cannot carry out all the physiological processes needed for its existence.

- Spirogyra cell/E will survive/multiply/grow; because there is no specialization among the cells/each cell can live on its own.  

 

(iii)     Differences between organisms C and E       

Volvox/C	Spirogyra/E
- Identical cells form round mass/colony/spherical	Identical cells are joined end to end in filament/filamentous;
- Chloroplasts are circular	Chloroplasts are spiral;
- Nucleus is inconspicuous	Nucleus s conspicuous;
- Flagella present/motile	Flagella absent/non-motile;
- Gelatinous sheet absent	Gelatinous sheet present;
- Pyrenoid absent	Pyrenoid present;
- Cells are dependent physiologically	Cells are independent physiologically;
- Division of labour takes place	No division of labour

(c) (i) Economic importance of D

• Harmful bacteria cause diseases in living things;
• they are responsible for food spoilage;
• useful bacteria are used industrially in the manufacture of some food items/butter/cheese/yoghurt/vinegar;
• they bring about decay;
• improve soil fertility;
• used in the production of some antibiotics/medicine.

 

(ii) Diseases in humans caused by the bacteria/B

• Gonorrhoea; syphilis; tuberculosis; cholera;
• dysentery; typhoid; pneumonia;
• cerebrospinal meningitis; tetanus; diphtheria;
• whooping cough/pertussis;
• food poisoning; any correctly named human bacterial disease.

 

(d) (i)  Structures on C and D used for locomotion
C- Flagellum/flagella/I
D- Flagellum/flagella/IV                                                       

 

(ii) Instrument to view D
Microscope(s)                                                                       

(e) (i) Similarities between organism D and C

• Both have organs of locomotion/flagellum/flagella;
• Both have protoplasm/cytoplasm;
• Both have cell wall.

                                                     
(ii) Similarities between organism D and a cell from organism E

• Both have cell wall;
• Both have protoplasm/cytoplasm.