This figure is a simplified electron micrograph drawing of a cell from a human pancreas. Pancreatic cells release protein enzymes into the small intestine a...
Question 1 Report
This figure is a simplified electron micrograph drawing of a cell from a human pancreas. Pancreatic cells release protein enzymes into the small intestine after food is eaten. The cell has many small bean-shaped organelles and a large number of flattened membrane sacs. These structures provide energy and process proteins before secretion. A student compared this cell with a red blood cell, which is specialised to carry oxygen in blood.
(a) What is organelle A? [1]
(b) Give the function of organelle A. [1]
(c) Describe why this pancreatic cell contains many organelles B. [2]
(d) Give one way in which a mature red blood cell is different from the cell in Fig. 1. [1]
Fig. 1 shows an experiment in which a student placed a cube of agar containing red dye into a beaker of clear water. The agar represents cytoplasm inside a large cell. Dye molecules moved from the agar into the water. The student made three cubes from the same batch of agar and measured the time until each cube became colourless. The investigation models why cells need a large surface area compared with their volume.
(a) What process causes dye to leave the agar cube? [1]
(b) Give the name of the boundary labelled A. [1]
(c) Describe why a smaller cube becomes colourless more quickly than a larger cube. [2]
(d) When cells become very large, what problem can occur with movement of substances into the cell? [1]
Answer Details
Pancreatic cell, (a) Organelle A is a mitochondrion. [1]
Pancreatic cell, (b) Mitochondria release energy by aerobic respiration. [1]
Pancreatic cell, (c) B is rough endoplasmic reticulum, a system of membrane sacs involved in protein synthesis or transport. Many are present because pancreatic cells make and secrete large amounts of enzyme protein. [2]
Pancreatic cell, (d) A mature red blood cell differs because it has no nucleus. It also contains haemoglobin and has a biconcave shape. [1]
Agar-cube investigation, (a) Dye leaves the agar by diffusion. [1]
Agar-cube investigation, (b) A is the surface, modelling a cell membrane boundary. [1]
Agar-cube investigation, (c) A smaller cube has a larger surface-area-to-volume ratio and a shorter diffusion distance. Dye can therefore leave more rapidly, so the cube becomes colourless sooner. [2]
Agar-cube investigation, (d) In a very large cell, substances enter too slowly because the diffusion distance is too great. [1]
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