iGCSE Biology (0610)-7.5 Absorption - iGCSE Style Questions Paper 4

Question

(a) The small intestine is lined with many villi and is adapted to absorb glucose.
Fig. 2.1 shows two villi from the lining of the small intestine.

(i) State the name of structure N in Fig. 2.1.
(ii) Cell M in Fig. 2.1 secretes mucus.
State the name of cell M.
(iii) State one other place in the body where mucus secreting cells are found.

(iv) Describe and explain how the structure of a villus is adapted for its function.

(b) State the name of the main blood vessel that takes blood from the small intestine to the liver.

(d) Some cells in the small intestine have many mitochondria.
Fig. 2.2 shows the variation in the average number of mitochondria found in three different types of cell.

Explain the differences in the average number of mitochondria in each type of cell.

▶️ Answer/Explanation

Solution

2(a)

(i) Lacteal

Explanation: Structure N is the lacteal, a lymphatic vessel in the villus that absorbs dietary fats.

(ii) Goblet cell

Explanation: Cell M is a goblet cell, which secretes mucus to protect the intestinal lining and lubricate food passage.

(iii) Trachea / Bronchi / Bronchioles

Explanation: Mucus-secreting cells are also found in the respiratory tract to trap dust and pathogens.

(iv) Villus Adaptations:

Microvilli: Increase surface area for faster absorption.
Thin epithelium: One-cell thickness reduces diffusion distance for nutrients.
Rich blood supply: Maintains concentration gradients for efficient diffusion.
Lacteals: Absorb and transport fats.

2(b) Hepatic portal vein

Explanation: This vessel carries nutrient-rich blood from the small intestine to the liver for processing.

2(c) Stem Cell Definition:

Unspecialized cells capable of mitosis.
Differentiate into specialized cell types (e.g., intestinal epithelial cells).

2(d) Mitochondrial Variation:

Heart muscle cells: High mitochondrial count for continuous ATP production to sustain contractions.
Intestinal epithelial cells: Many mitochondria power active transport of nutrients.
Red blood cells: No mitochondria—maximizes space for hemoglobin and oxygen transport.

Question

(a) Complete the sentences about human teeth. The process of taking food into the mouth is called ……….. . Flat sharp‑edged teeth at the front of the mouth, called ………. , are used for biting off pieces of food. The ………. and ……… are the large teeth towards the back of the mouth that are used for ………. the food.

(b) Fig. 6.1 is a diagram of a villus.

(i) Draw labels and label lines on Fig. 6.1 to identify a capillary and a lacteal.

(ii) State the part of the digestive system where villi are located.

(iii) State the function of the lacteal.

(c) Describe the pathway taken by the products of protein digestion from the villi to the liver.

▶️ Answer/Explanation

Solution

Ans

(a) ingestion ; incisors ; molars and premolars ; chewing / grinding / crushing / mashing / masticating

Explanation:

Ingestion is the process of taking food into the mouth.
Incisors are the sharp front teeth used for cutting food.
Molars and premolars are large back teeth used for grinding food.

(b)(i) One label line should point to a capillary (a tiny blood vessel) and another to the lacteal (a lymphatic vessel in the villus).

(b)(ii) small intestine

(b)(iii) absorption / transport of, fatty acids / glycerol / fat / lipids

Explanation: The lacteal absorbs and transports fats in the form of fatty acids and glycerol.

(c)

Amino acids (from protein digestion) enter capillaries in the villi.
They are carried in the blood plasma via the hepatic portal vein.
Finally, they reach the liver for processing.

iGCSE Biology (0610)-7.5 Absorption – iGCSE Style Questions Paper 4

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