KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS - ATIKA SCHOOL

Explain how the kidney are structurally adapted to perform their functions

21/4/2022

Explain how the kidney is adapted to its function

Adaptations for ultra-filtration

It has a selective permeable Bowman's capsule that only allows food substances and food products to pass through but prevents the passage of plasma proteins and blood cells.
The afferent arteriole is highly branched in the glomerulus and this provides a larger surface area for blood to flow in the kidney for filtration.
The efferent arteriole have a narrower lumen than the afferent arteriole and this builds up higher pressure necessary for ultra-filtration.

Adaptations for reabsorption

Kidney tubules are long and coiled and this provides a larger surface area for reabsorption and more time is allowed for reabsorption of the useful products.
The kidney tubules are highly vascularised to ensure constant removal of reabsorbed substances hence creating more room for further reabsorption.
The microvilli on the inner surface of epithelial lining of proximal convoluted tubules provide a larger surface area for reabsorption.
Cells lining the kidney tubules/proximal convoluted tubule have numerous mitochondria which provide energy for active reabsorption of glucose, amino acids, vitamins and mineral salts.
The loop of henle is U -shaped and this creates a multiple counter current system for efficient reabsorption of substances

The equation below represents a process in a mammalian liver

31/10/2021

The equation below represents a process in a mammalian liver

(a) Name the process shown by the equation above (1mk)

Deamination;

(b) List down a carbohydrate that is;-

(i) Stored in the mammalian liver (1mk)

Glycogen;

(ii) Found in abundance in mammalian blood (1mk)

Glucose;

Name two functions of sodium in human body

30/10/2021

Name two functions of sodium in human body (2mks)

Formation of the harmone thyropine;
Nerve impulse transmission;

The set up below shows apparatus to demonstrate a certain biological process

7/9/2021

(a) What biological process was being investigated in the experiment (1mk)

Gas produced during anaerobic respiration

(b)Write down a word equation that represents the reaction above (1mk)

Glucose > Ethanol + Carbon (IV) oxide +Energy

(c) In the above set up, why was it important to boil and cool glucose before adding yeast? (1mk)

To remove O2; cooling to provide suitable temperature for enzymatic reactions/ avoid destroying/killing yeast

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