BIOLOGY PRACTICAL QUESTIONS AND ANSWERS – RACHUONYO DISTRICT

 BIOLOGY PRACTICAL QUESTIONS – RACHUONYO DISTRICT

 Each school will need 20g of yeast powder for every to candidates picked and sealed in  polythene

papers and labeled substance K.

 To schools – Substance K is to reach school on the morning of the examination packed   substance ‘K’ delivered to schools on the day of Biology examination

 Each candidate will require the following:-

• 4 test-tubes with tightly fitting corks
  
• 6ml of 10% glucose in a test tube
  
• 3 labels per candidate
  
• 6ml of distilled water in a test tube
  
• Source of heat
  
• 2cm by 2cm liver piece
  
• Dilute hydrogen peroxide (20 volumes)
  
• About 2g of substance K
  
• Substance K to be provided by RAEC on the morning of examination day)
  

1.  During a visit to a museum, students were shown ten specimens of invertebrates on display.

 The teacher provided a dichotomous key to enable them classify each specimen on display.

 Five of the specimens are shown in the photographs below:

DICHOTOMOUS KEY

 1. a. Animal with flattened body Go to 9

    b. Animal without flattened body Go to 2

 2. a. Animal with body in shell Mollusca

    b. Animal without shell  Go to 3

 3. a. Animal with segmented body Go to 4

  b. Animal with body not segmented Nematoda

 4. a. Animal with jointed appendages Go to 6

    b. Animal without jointed appendages Go to 5

 5. a. Animal with long and cylindrical body Annelida

  b. Animal with short stout body Trematoda

 6. a. Animal with antennae  Go to 7

    b. Animal without antennae Go to 8

 7. a. Animal with one pair of antennae Insecta

    b. Animal with more than one pair of antennae  Crustacea

 8. a. Animal with pincer like mouth parts Arachnida

    b. Animal with sucking mouth parts Acarina

 9. a. animal with long ribbon like body Cestoda

  b. Animal with circular body Crinoidea

 (a) Use the dichotomous key to identify the taxonomic group of each of the five specimens in

the photographs. In each case, show the sequence of steps e.g. 1a, 2b, 7b e.t.c. in the key

that you followed to arrive at identity of each specimen

 (b) State the phylum to which animal G belong

 (c) Apart from jointed appendages, state 2 other distinguishing characteristics of the phylum

named in B above  

2.  The photomicrograph below represents parts of 2 adjacent cells as seen under an electron

 microscope. Study it and answer the questions that follow:-

 (a) Use the table below to name P, Q, R, S and T. For each organelle, state one function  

 (b) The magnification of the cells in this micrograph is x 10,000. Use a ruler to measure the

radius of the nucleus between X and Y in millimeters. Calculate the actual radius of the

nucleus before magnification in mm

Length………………………………………mm

Actual radius of nucleus

3.  You are provided with 10% glucose solution and substance K. place equal amounts of the

  glucose solution in test tubes labeled 1, 2 and 3. Divide the substance K into 3 equal portions.

  To one portion, add 2ml of water and boil, cool it down. Pour this mixture into test tube 1

 Add another portion of substance K to test-tube 2 and shake.  

  Put 2ml of distilled water in test tube 3. Close the 3 test-tubes tightly using well fitting

corks, and allow the set-ups to stand for at least 20 minutes

 (a) Record your observation:   (i) Test tube 1   (ii) Test tube 2   (iii) Rest tube 3  

 (b) (i) Name the process being investigated in the experiment  

(ii) Write down an equation for this process

(iii) In which organelle does the process take place

  (c) (i) Suggest the identity of substance K  

(ii) Account for the results in test-tube 1  

 (d) Cut a small piece of liver 2cm by 2cm. drop it into the test tube containing dilute

hydrogen peroxide. Leave for 2 minutes

(i) State your observation

(ii) Account for your observations

RACHUONYO DISTRICT BIOLOGY PRACTICAL MARKING SCHEME (ANSWERS)

1.   a)

Each correct identify 1mk

Each correct step 1mk

Reject wrong order of steps

Reject wrong spelling for identify

Identify tied to steps (if steps is wrong then reject identity)  

b) Arthropoda√ 1mk Rj wrong spellings  

c) Segmented body√/     Exoskeleton (made of chitia)√

2  a)

Rj. Wrong spelling for name but mark function of right  

b) Length – 31mm

c) actual radius = photomicrograph length  

Magnification

=31 √  

10,000

= 0.0031mm√

3.  a) i) No bubbles/no effervescence/no observable change

  ii) Bubble/effervescence/foam/increase in warmth

  iii) No bubbles/no effervescence/no observable change

b )i) fermentation (anaerobic) respiration

ii)C₆H1₂O₆ 2C₂H₅OH +CO₂ +Energy

  Glucose ethanol +carbon (iv) oxide +energy

iii) mitochondrion/mitochondria

c) i) yeast/enzyme/catalyst (

  ii) Boiling denatures yeast/enzyme; hence glucose not broken down/respired; to

produce Carbon (IV) oxide gas (which forms bubbles)  

d) i) bubbles/effervescence/foam  

ii) Catalyst (in liver); breaks down hydrogen peroxide; to form water and oxygen

(which forms bubbles);