7.5. Absorption
A subsection of Biology, 0610, through 7. Human nutrition
Listing 10 of 58 questions
Explain why food has to be digested. shows a section through the human body. J K L M Identify the structures labelled on . Write your answers in Table 8.1. Table 8.1 structure name J K L M In a medical investigation the number of villi in four people was compared. The results given in Table 8.2 show the average number of villi present in 1 cm2 of ileum wall. Table 8.2 person average number of villi per cm2 P Q R S Calculate the difference in the number of villi between person P and person S. difference = per cm2 Further investigations showed that person Q could absorb digested food more rapidly than the other people. Use the information in Table 8.2 to explain this result.
0610_w15_qp_21
THEORY
2015
Paper 2, Variant 1
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Cells in the lining of the stomach secrete gastric juice, which contains hydrochloric acid and pepsin. State two roles of hydrochloric acid in the stomach. Describe the function of pepsin. Define the term assimilation. There are stem cells in the epithelial tissue that forms the lining of the stomach. Explain why these stem cells are necessary. The epithelial cells of the small intestine have many microvilli. State the role of the microvilli. Lactobacillus is a type of bacterium. A study was carried out to investigate the ability of Lactobacillus to attach to the epithelial cells that form the lining of the small intestine. Researchers added Lactobacillus bacteria to epithelial cells that had been grown in Petri dishes. Every 15 minutes, the researchers estimated the average number of bacteria that were attached to the epithelial cells in the Petri dishes. The results are shown in . time / minutes average number of bacteria attached to epithelial cells
0610_w19_qp_42
THEORY
2019
Paper 4, Variant 2
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shows several villi from the ileum, which is part of the small intestine. State the name of one other part of the small intestine. lacteal goblet cells area enlarged in shows the tip of a villus in more detail. goblet cell microvilli epithelial cells The epithelial cells of the villi absorb nutrients by diffusion and active transport. Describe how active transport differs from diffusion. Explain the importance of the microvilli shown in . Goblet cells provide protection for the epithelial cells that line the intestine. State the name of the protective substance produced by goblet cells. Suggest why a protective substance is necessary in the intestines. shows a lacteal in the centre of each villus. Describe the roles of lacteals. Complete Table 1.1 by identifying the level of organisation of each structure. Choose your answers from the list. Each word or phrase may be used once, more than once or not at all. cell cell structure organ organ system organism tissue Table 1.1 structure level of organisation gall bladder endoplasmic reticulum intestinal epithelium ileum Many fungi are decomposers that feed on dead plants. The fungi secrete enzymes to digest large molecules. Students made an extract from a species of fungus. The extract contained digestive enzymes. The students carried out an investigation to find out if amylase and pectinase were present in the fungal extract. They made agar plates by filling Petri dishes with agar jelly containing either starch or pectin. They cut four holes of the same size in the agar jelly in each Petri dish. The holes in each Petri dish contained the same volume of: A – 1% amylase solution B – 1% pectinase solution C – distilled water D – fungal extract. The Petri dishes were kept at 27 °C for four days. After this time a dye was poured into each dish to stain the areas where starch and pectin remained. shows drawings of the stained agar in the Petri dishes. The clear zones indicate the areas where no starch or pectin remained. A B C D D C B A Key: stained area clear zone hole in agar jelly Petri dish containing pectin in agar jelly Petri dish containing starch in agar jelly State what conclusions can be made about the enzymes in the fungal extract and give evidence from to support your conclusions. The investigation was repeated but at 5 °C instead of at 27 °C. Predict the effect of the lower temperature on the results.
0610_w21_qp_42
THEORY
2021
Paper 4, Variant 2
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Questions Discovered
58