2.2. Carbohydrates and lipids
A subsection of Biology, 9700, through 2. Biological molecules
Listing 10 of 368 questions
is a photomicrograph showing part of a transverse section through the root of an iris, Iris germanica. Irises are herbaceous monocotyledons. These plants have the same transport tissues as herbaceous dicotyledons, but the transport tissues are distributed differently. In monocotyledons, the central tissue in the root is parenchyma (packing tissue). R S T parenchyma ×120 Cells R, S and T in are found in different tissues. Name the tissues in which the cells labelled R, S and T are found. tissue in which cell R is found tissue in which cell S is found tissue in which cell T is found Outline the role of the tissue in which cell R is found in . State an example of an organic compound that is translocated in the root of an iris. The electron micrograph in shows a section through some root cells in an onion, Allium cepa. ×6250 On , draw a label line and label it with the letter P to identify one plasmodesma. Table 3.1 contains information about four polysaccharides found in animals or plants. Complete Table 3.1 by filling in the missing information. Table 3.1 polysaccharide monomer glycosidic bondfunction amylopectin α-glucose 1,4 and 1,6 energy storage in plants amylose 1,4 energy storage in plants cellulose β-glucose structural role in plant cell walls glycogen α-glucose 1,4 and 1,6
9700_m24_qp_22
THEORY
2024
Paper 2, Variant 2
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Cereal crops, such as sorghum and rice, are a major source of nutrients all over the world. Explain why cereal crops are important components of many people’s diets. Alpha amylase is an enzyme produced in germinating seeds, where it hydrolyses starch. shows the effect of temperature on alpha amylase in germinating seeds of sorghum and rice. enzyme activity / arbitrary units temperature / ˚C sorghum rice Name the part of the seed that contains starch. With reference to , compare the effects of temperature on alpha amylase in sorghum and rice. With reference to the types of bonding in proteins, suggest how differences in the tertiary structure of alpha amylase in rice and sorghum could explain the differences in their activities shown in . Sorghum does not grow well at low temperatures. An investigation was carried out into the response of sorghum to low temperatures at different light intensities. • Sorghum plants were kept at 25 °C in a light intensity of 215 W m-2 for several weeks, and then at 10 °C for three days. • The temperature was then increased to 25 °C again for seven days. • The investigation was repeated at light intensities of 170 W m-2 and 50 W m-2. • Day length and carbon dioxide concentration were kept constant throughout. The uptake of carbon dioxide, as mg CO2 absorbed per gram of leaf dry mass, was measured • at 25 °C before cooling • at on each of the three days at 10 °C • for seven days at 25 °C. The results are shown in Table 4.1. Table 4.1 light intensity / W m-2 carbon dioxide uptake / mg CO2 g-1 at 25 °C, before cooling during cooling at 10 °C at 25 °C (mean over days 4 to 10) day 1 day 2 day 3 50.1 3.0 0.4 0.2 0.2 48.2 5.5 2.9 1.2 1.5 22.4 3.0 1.2 0.7 9.2 With reference to Table 4.1 describe and explain the effect of light intensity on the rate of carbon dioxide uptake before cooling describe the effect of light intensity on the ability of sorghum plants to survive cooling.
9700_s10_qp_42
THEORY
2010
Paper 4, Variant 2
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Cereal crops, such as sorghum and rice, are a major source of nutrients all over the world. Explain why cereal crops are important components of many people’s diets. Alpha amylase is an enzyme produced in germinating seeds, where it hydrolyses starch. shows the effect of temperature on alpha amylase in germinating seeds of sorghum and rice. enzyme activity / arbitrary units temperature / ˚C sorghum rice Name the part of the seed that contains starch. With reference to , compare the effects of temperature on alpha amylase in sorghum and rice. With reference to the types of bonding in proteins, suggest how differences in the tertiary structure of alpha amylase in rice and sorghum could explain the differences in their activities shown in . Sorghum does not grow well at low temperatures. An investigation was carried out into the response of sorghum to low temperatures at different light intensities. • Sorghum plants were kept at 25 °C in a light intensity of 215 W m-2 for several weeks, and then at 10 °C for three days. • The temperature was then increased to 25 °C again for seven days. • The investigation was repeated at light intensities of 170 W m-2 and 50 W m-2. • Day length and carbon dioxide concentration were kept constant throughout. The uptake of carbon dioxide, as mg CO2 absorbed per gram of leaf dry mass, was measured • at 25 °C before cooling • at on each of the three days at 10 °C • for seven days at 25 °C. The results are shown in Table 4.1. Table 4.1 light intensity / W m-2 carbon dioxide uptake / mg CO2 g-1 at 25 °C, before cooling during cooling at 10 °C at 25 °C (mean over days 4 to 10) day 1 day 2 day 3 50.1 3.0 0.4 0.2 0.2 48.2 5.5 2.9 1.2 1.5 22.4 3.0 1.2 0.7 9.2 With reference to Table 4.1 describe and explain the effect of light intensity on the rate of carbon dioxide uptake before cooling describe the effect of light intensity on the ability of sorghum plants to survive cooling.
9700_s10_qp_43
THEORY
2010
Paper 4, Variant 3
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Questions Discovered
368