Seatwork
LOWER SECONDARY
AY 2024-2025
Student’s Name
Grade 8
Instructions:
Answer the following questions in the spaces provided. Write in dark blue or black pen.
1
The picture below shows sections of three blood vessels: an artery, a capillary and a vein.
(a)
State one function for each of the blood vessels.
artery :
1 carries blood from the heart / delivers blood to tissues ; OR
2 withstands / maintains / transports blood at, high pressure ; OR
3 transports oxygenated blood except pulmonary (artery) ;
capillary :
4 exchange of substances to, tissues / cells ; OR
5 allows diffusion / described as movement of named gas ; OR
6 allows, filtration / white cells to escape / forms tissue fluid ; OR
7 allows (re)absorption ; OR
8 heat, exchange / loss / gain ;
vein :
9 transports blood, to the heart / from tissues ; OR
10 transports blood at low pressure ; OR
11 transports deoxygenated blood except pulmonary (vein) ;
(b)
Explain how the structure of the artery is adapted to its function.
1 small / narrow, lumen / space for blood / opening / hole ;
[2]
2 thick / big, wall ; 3 elastic (tissue / fibres) ;
4 stretches / expands ;
5 recoils ;
6 muscle ;
7 flexible to allow expansion / prevents rupture / prevents bursting ;
8 fibrous, tissue / outer layer ; A collagen
9 withstands / maintains, pressure ;
Any 2 from following key
Biology 8
Page 1 of 4
Seatwork
LOWER SECONDARY
AY 2024-2025
(c)
Explain how valves help the transport of blood in veins.
1 blood fills valve / valve closes (in vein) ;
2 to prevent backflow ;
[2]
3 blood flows in one direction / towards heart / prevents flowing away from heart ;
(d)
What is the function of corronary arteries ?
1 carry nutrients and oxygen for the heart
[2]
2 remove waste products from the heart
(e)
Explain how an unhealty diet can lead to coronary heart disease.
1 A diet high in saturated fats and cholesterol leads to plaque buildup in arteries.
2 Plaque narrow artery lumen, increase pressure / less elastic
[2]
3 Increased risk of high blood pressure, heart attack, and stroke.
Any 2
2
The picture below shows the some of the blood cells.
(a)
State what are P: Red blood cell, Q: lymphocyte and R: phagocyte
(b)
Explain the function of cell P and how is the cell adapted to its function
[3]
Function: Transports oxygen around the body using hemoglobin.
[3]
Adaptations:
•
Biconcave shape increases surface area for gas exchange.
•
Lacks a nucleus to maximize space for hemoglobin.
•
Flexible membrane to squeeze through capillaries.
Any two
(c)
Explain the function of cell Q and R
R: Q: Engulfs / digests / kill pathogens through phagocytosis.
Q R: Produces antibodies to neutralize / mark / immobilize pathogens.
Biology 8
[2]
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Seatwork
LOWER SECONDARY
AY 2024-2025
(d)
The picture below shows the action of cell Q and R protect our body from pathogen.
i) What is the name
of molecule S?
Antibody
[1]
ii)
Describe how bacteria are destroyed by cell Q and R based on the diagram.
1 Lymphocytes (Q) produce antibodies that bind to pathogens.
2 Antibodies mark / immobilize pathogens for destruction or neutralize them directly
3 Phagocytes (R) engulf marked / immobilized bacteria by phagocytosis.
4 Enzymes digest the bacteria inside the phagocyte.
3
(a)
[3]
Thrombin is an enzyme that catalyses the blood clotting reaction.
State what are X,Y and Z then
explain the process of blood clotting
process based on the diagram, and
complete the diagram
X: Thromboplastin (1)
Y: Prothrombin (1)
Z: Fibrin (1)
1 Injured tissue causing platelets to
release thromboplastin (X) (1)
2 Thromboplastin converts
prothrombin (Y) into thrombin in the
presence of calcium ions (1)
3 Thrombin converts fibrinogen into
fibrin (Z), which forms a mesh to
trap red blood cells and clot the
wound (1)
[6]
Total (6) marks
4
(a)
Lymph vessels contain lymph fluids that move in a similar way to the blood flowing in veins.
Explain the mechanism that cause the movement of lymoh fluids in the lymph vessels.
1 Lymph moves due to muscle contractions squeezing the vessels. (1)
2 Valves prevent backflow, ensuring one way flow movement (1)
[2]
Biology 8
Page 3 of 4
Seatwork
LOWER SECONDARY
AY 2024-2025
(b)
Explain why the lymph fluids that leave the ileum have high concentrations of fat droplets.
1 The small intestine absorbs fats into the lacteals, (1)
[2]
2 lacteal vessels are part of the lymphatic system. (1)
Biology 8
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