16.1. Passage of information from parents to offspring
A subsection of Biology, 9700, through 16. Inheritance
Listing 10 of 75 questions
Flowers are the organs of sexual reproduction in plants. Before fertilisation and seed development can take place, pollination must occur. This can be either self-pollination or cross-pollination, and can be carried out by insects or by wind. Explain the meaning of the term self-pollination. Explain why cross-pollination may be more beneficial to a species than self-pollination. In maize, wind pollination occurs. An investigation was carried out to find out how the length of time that maize pollen is in the air affects its ability to bring about fertilisation in a female flower. • Pollen grains were removed from maize flowers and left exposed to the air for varying times. • The pollen grains were then placed onto groups of female flowers. • The groups of fertilised flowers developed into ‘ears’, each containing many seeds. The number of seeds per ear was counted. The results are shown in . time of exposure of pollen to air / minutes number of seeds produced per ear Describe the effect of exposure to the air on maize pollen. A wild relative of maize, called teosinte, grows in Mexico. There are concerns that pollen from genetically-modified maize could pollinate wild teosinte and transfer new genes to it. Suggest how the results shown in could be used to devise strategies that would reduce the possibility of this happening.
9700_w12_qp_41
THEORY
2012
Paper 4, Variant 1
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Flowers are the organs of sexual reproduction in plants. Before fertilisation and seed development can take place, pollination must occur. This can be either self-pollination or cross-pollination, and can be carried out by insects or by wind. Explain the meaning of the term self-pollination. Explain why cross-pollination may be more beneficial to a species than self-pollination. In maize, wind pollination occurs. An investigation was carried out to find out how the length of time that maize pollen is in the air affects its ability to bring about fertilisation in a female flower. • Pollen grains were removed from maize flowers and left exposed to the air for varying times. • The pollen grains were then placed onto groups of female flowers. • The groups of fertilised flowers developed into ‘ears’, each containing many seeds. The number of seeds per ear was counted. The results are shown in . time of exposure of pollen to air / minutes number of seeds produced per ear Describe the effect of exposure to the air on maize pollen. A wild relative of maize, called teosinte, grows in Mexico. There are concerns that pollen from genetically-modified maize could pollinate wild teosinte and transfer new genes to it. Suggest how the results shown in could be used to devise strategies that would reduce the possibility of this happening.
9700_w12_qp_42
THEORY
2012
Paper 4, Variant 2
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The photomicrographs in show stages of the mitotic cell cycle occurring in the root tip of the onion, Allium sp. They are all of the same magnification. Stages A to C are in the correct sequence and stages K to N are not in the correct sequence. stages in correct sequence stages not in correct sequence A B C K L N M Name stages A and C. A C Put stages K to N in the correct sequence, starting with the stage that immediately follows stage C. C Explain how the behaviour of the chromosomes and spindle during stage L in ensures that the two daughter cells will be genetically identical.
9700_w15_qp_22
THEORY
2015
Paper 2, Variant 2
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The early development of an animal involves divisions of the zygote and daughter cells by mitosis to form an embryo consisting of genetically identical cells. shows several cells at various stages of the cell cycle in an embryo of whitefish, Coregonus artedi. magnification ×1200 microtubules A C B Name the stage of mitosis in cell A and in cell B, shown in . A B shows microtubules in the cells that are dividing. Describe the role of microtubules in mitosis. State what happens in cell C, shown in , until two new cells are formed. The cells produced in the developing whitefish are genetically identical. Identify and explain two events that occur during the cell cycle that lead to daughter cells being genetically identical.
9700_w22_qp_23
THEORY
2022
Paper 2, Variant 3
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Questions Discovered
75