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SEX and FERTILISATION 1. 2. 3. In humans which of the following gametes are not normally formed? A an egg with an X chromosome B an egg with a Y chromosome C a sperm with an X chromosome D a sperm with a Y chromosome The DNA of a chromosome carries information which determines the structure and function of A fats B bases C carbohydrates D proteins In humans, which of the following gametes would determine a male offspring at fertilisation? A an egg cell with an X chromosome B an egg cell with a Y chromosome C a sperm cell with an X chromosome D a sperm cell with a Y chromosome 1 4. The table below gives information about chromosomes in some human cells. Which line in the table is correct? Cell 5. Number of Number of chromosome sets chromosomes A nerve 2 23 B egg 1 23 C lymphocyte 1 46 D sperm 2 23 Which of the following is a correct description of a chromosome? A a chain of DNA bases B a chain of RNA bases C a chain of amino acids D a chain of sugar molecules 2 6. The diagram below represents the transmission of sex determining chromosomes from parents to offspring. Gametes mother father P R Q S Which line in the table below correctly identifies the sex chromosomes for the gametes P, Q, R and S? Gamete P 7. Gamete Gamete Gamete Q R S A XX XX XY XY B X X X Y C XX XY XX XY D X Y X Y Which line in the table below names gametes and their sites of production in a flowering plant? Male gamete Site of production Female gamete Site of production A sperm testes egg ovule B pollen nucleus anther egg cell ovary C sperm anther egg ovary D pollen nucleus testes egg cell ovule 3 8. 9. In humans, all sperm contain A an X chromosome B a Y chromosome C an X and Y chromosome D either an X or a Y chromosome The diagram below shows the main parts of a flower. Which line in the table identifies X and the type of gamete it produces? Name of X Type of gamete produced A ovary male B ovary female C anther female D anther male 4 10. (a) The diagram below shows meiosis and fertilisation in humans. Cell A (in testis) from ovary Meiosis Cell B Fertilisation Cell D (i) (b) Copy and complete the following table by naming the cells and stating the number of chromosomes present in each. Cell Name of cell A testis cell B sperm Number of chromosomes C 23 D 46 (ii) Describe what happens during fertilisation. (i) Name a structure in a cell which is composed of a chain of DNA bases. (ii) Explain the importance of the order of the DNA bases to the functioning of a cell. 5 11. (a) The diagram below shows all the chromosomes found in a human skin cell. Identify the sex of the person and give a reason for your answer. (b) Copy the following sentences and underline one option in each set of brackets to make the sentences correct. During meiosis, matching chromosomes pair and separate producing gametes with one set of body cells two sets chromosomes. A zygote is produced from these cells by random assortment fertilisation . 6 12. (a) Copy and complete the table below to give the site of production and number of chromosomes of each type of gamete. Human gamete Site of production Number of chromosomes egg sperm (b) The diagram below shows the chromosome complement of a cell about to divide to form gametes. (i) How many sets of chromosomes does this cell contain? (ii) Name the type of cell division which produces gametes. (iii) The following diagram shows one way in which these chromosomes may line up during cell division. Copy and complete the diagram below to show one other way in which the chromosomes may line up. 7 12. Contd. (c) Chromosome pairs line up in a variety of ways. Explain why this random assortment is important. 8 13. (a) The diagram below shows a yeast cell. (i) Name the structure shown in the yeast cell which contains the genetic information. (ii) A molecule consisting of chains of bases is contained in chromosomes. (A) Name this molecule. (B) Explain how this molecule controls cell activities. (b) Gamete production is essential to sexual reproduction. (i) Name the division of the nucleus that occurs during gamete production. (ii) Name the process occurring during this division that increases variation. (iii) Copy the following sentences and underline one option in each set of brackets to make the sentences correct. The number of chromosomes in gametes is half twice the number found in body cells. The zygote is formed by half twice fusion division and contains the number of chromosomes in a gamete. 9 14. You may use a labelled diagram where appropriate. Give an account of gamete formation in human females. 15. Describe the structure of chromosomes. Explain how chromosomes determine the characteristics of an organism. 16. The diagram below shows the two stages that result in the formation of offspring in animals. cell in testis cell in ovary Stage 1 Stage 2 offspring (a) Describe what happens at each stage. (b) Explain how variation is brought about during each stage. 10 GENETICS and INHERITANCE 17. A true breeding red bull is mated with a true breeding white cow. The offspring are all intermediate in colour. (roan) This type of inheritance is 18. A polygenic B recessive C co-dominant D dominant In tomato plants the allele for red fruit is dominant to the allele for yellow fruit. If a heterozygous tomato plant is crossed with a plant which produces yellow fruit, the expected phenotype ratio of the offspring would be A 3 red : 1 yellow B 1 red : 3 yellow C 1 red : 2 yellow D 1 red : 1 yellow 11 19. Achoo syndrome is a dominant characteristic in humans which causes the sufferer to sneeze in response to bright light. A woman who is homozygous for the syndrome and a man is unaffected have children. What proportion of their children would be expected to have Achoo syndrome? 20. A 0% B 25% C 50% D 100% When a plant with red flowers was crossed with a plant with white flowers, the F1 plants had pink flowers. The F1 plants were then self-fertilised. What ratio of flower colours would be found in the F2 generation? A 1 red : 2 white B 1 white : 2 pink C 1 red : 2 pink : 1 white D 1 red : 1 pink : 1 white 12 Questions 21 and 22 refer to the information below. In mice, the dominant form (B) of one gene determines black coat colour; brown coat colour results from the recessive form (b) of the gene. A cross between two mice is shown below. P BB x bb F1 Bb 21. 22. Which of the following shows all the possible genotypes of the F2 generation? A BB and Bb B bb and Bb C BB and bb D BB, Bb and bb What proportion of the F2 generation would be expected to have black coats? A B C D 1 4 1 2 2 3 3 4 13 23. 24. 25. If an inherited characteristic is controlled by alleles of more than one green, then the type of inheritance is called A true bleeding B polygenic C co-dominant D monohybrid Which term refers to a description of a characteristic of an organism? A genotype B phenotype C allele D natural selection Which term refers to forms of a gene controlling the same characteristic? A genotypes B phenotypes C alleles D dominant 14 26. In humans the length of the big toe is controlled by a single gene which has two alleles. A father is homozygous for short big toe. The mother has long big toes. All of their children have short big toes. (a) Copy and complete the following sentences by underlining the correct word in each pair, using the information above. Long Short big toe is the dominant form of this gene. The mother is homozygous and the children are all heterozygous homozygous heterozygous . 15 26. Contd. (b) The ability to roll the tongue is controlled by another gene in humans. The allele for tongue rolling (R) is dominant to the allele for non tongue rolling (r). The diagram below shows the occurrence of this tongue rolling gene. Key Female Male tongue roller non tongue roller mother father Kate Jill Ben Jamie (i) With respect to the tongue rolling gene, state Jamie’s phenotype and Ben’s genotype. (ii) Kate has a son and his father is homozygous dominant for the characteristic. What is the percentage chance that the son is a tongue roller? (iii) State the two sex chromosomes present in Jill’s body cells. 16 27. (a) The table below shows the results of a study into the phenotypes of two pairs of human adult identical twins. Identical twins were used in this study as they have the same genotype. One pair of identical twins had been raised together since birth. The second pair had been separated since birth and raised by different families. Phenotype Appearance of twins Appearance of twins raised together raised apart P Q R S Eye colour blue blue brown brown Height (cm) 175 174 180 176 Blood group A A O O Hand span (cm) 23 23.5 25 23 From the results, copy and complete the following table by using tick(s) to show whether each phenotype was affected by genes, the environment or both. Phenotype Affected by genes Affected by environment Eye colour Height Blood group Hand span (b) In another study into plant phenotypes, leaf lengths were found to vary across a wide range. What term is used to describe this type of variation? 17 28. (a) In peas the height of the plant is controlled by one gene which has two alleles. T represents the dominant allele for tall stems. t represents the allele for short stems. True breeding, tall-stemmed pea plants were crossed with short-stemmed pea plants to produce the F1 generation. (i) State the genotype of the parents. (ii) State the phenotypes of the F1 plants. (iii) Plants from the F1 generation were crossed to produce the F2 generation of plants. State the phenotypes and their expected ratio in the F2 generation. 18 28. Contd. (b) Seeds from true breeding, tall-stemmed pea plants were provided with different growing conditions as shown in the diagrams below. (i) Compare the expected appearance of the plants in each group. (ii) What term is used to describe the effect of different conditions on the phenotype of an organism? 19 29. The diagram below shows the occurrence of tongue rolling in a family. (a) State the dominant form of the gene. (b) Identify the individuals in the F1 generation. (c) (i) Use the information in the diagram to copy and complete the table below. Individual Genotype A B C G L (ii) Name an individual from the table who is heterozygous for the gene. 20 30. (a) Name the male gametes and their site of production in a flower. (b) Tomato plants were used in an experimental monohybrid cross. The parental phenotypes were cut leaf and potato leaf as shown in the diagrams below. cut leaf potato leaf The parent plants were both true breeding. The F1 plants were self-pollinated. The F2 generation contained 80 plants with the cut leaf genotype and 20 plants with the potato leaf genotype. (i) Explain what is meant by the term true breeding. (ii) State which characteristic is dominant and give a reason. (iii) The results obtained in the F2 generation differ from the expected results. (iv) Suggest one reason why the results obtained differ from the expected results. 21 31. (a) In the fruitfly Drosophila melanogaster, the dominant form (G) of one gene determines grey body colour; black body colour results from the recessive form (g) of the gene. The genotypes of the parent flies used in a cross are shown below. GG gg (i) State the genotype(s) of the F1 offspring of this cross. (ii) Copy the table below and decide if each of the following statements about this cross is True or False, and tick () the appropriate box. If the statement is False, write the correct word in the Correction box to replace the word underlined in the statement. Statement True False The different forms of the gene are hybrids. The parents in this cross are true breeding. The F1 flies are homozygous. 22 Correction 31. Contd. (a) Contd. (iii) Two flies from the F1 were allowed to breed together. This produced 56 grey flies and 14 black flies in the F 2. Express this result as a simple whole number ratio. (grey flies : black flies) (iv) The expected ratio of grey flies to black flies in the F2 is 3:1. Suggest why the observed ratio was different from the expected ratio. (b) In a study of variation, a group of students collected information on the heights and blood groups of a class. For each variation state whether it is continuous or discontinuous. (c) Polygenic inheritance occurs as a result of the interaction of several genes. Give an example of polygenic inheritance in humans. 23 32. In fowl, the dominant form (R) of one gene determines rose comb shape; single comb shape results from the recessive form (r) of the gene. The diagram below shows the results of two crosses. Cross 1 parents True-breeding rose comb fowl Cross 1 offspring True-breeding single comb fowl all rose comb fowl Cross 2 parents Rose comb fowl from x Cross 1 offspring Single comb fowl Cross 2 offspring Single comb fowl Ratio (a) (i) (ii) Rose comb fowl 1 : 1 Which offspring contains only one phenotype? Copy and complete the Punnet square below to show the genotypes of the gametes of the Cross 2 single comb parent and the genotypes of the offspring produced. Genotypes of gametes of Cross 2 single comb parent Genotypes of R gametes of Cross 2 rose comb parent r 24 32. Contd. (b) Copy the table below and decide if each of the following statements is True or False, and tick () the appropriate box. If the statement is False, write the correct word in the Correction box to replace the word underlined in the statement. Statement True False A characteristic controlled by many genes is called co-dominant. The gene for comb shape has two different alleles. True breeding is another way of describing a homozygous individual. 25 Correction GENETIC ENGINEERING 33. In 1997 the USA planted 8.2 million hectares of land with genetically engineered crops. By 1998, this had increased to 20.5 million hectares. What was the percentage increase in the area sown between 1997 and 1998? 34. A 12.3% B 66% C 150% D 166.7% Genetic engineering can be used to alter bacterial cells in order to produce human insulin. The stages in the process are: 1. insulin gene extracted from a human cell 2. bacteria divide and produce large quantities of human insulin 3. plasmid is removed from bacterial cell and ‘cut’ open 4. insulin gene is inserted into bacterial plasmid. The correct sequence of these stages is A 1, 3, 4, 2 B 1, 3, 2, 4 C 3, 4, 2, 1 D 3, 1, 2, 4 26 35. The table below shows the relationship between planting density and the mass of seed harvested for a trial cereal crop. 4 Mass of seed harvested (grams per square metre) 60 8 86 16 104 32 77 128 22 Planting density (number of plants per square metre) The reason a low mass of seed was harvested when the planting density was 128 plants per square metre was 36. A less disease at high planting densities B more nutrients available C more competition for light and nutrients D less space for weeds Which term refers to the process by which organisms that are better adapted to their environment survive and breed? A Meiosis B Natural selection C Selective breeding D Genetic engineering 27 37. The graph below shows the average number of peppered moths in a woodland in June of each year over a 10 year period. Studies have shown that an increase in the number of dark moths is related to an increase in the level of pollution in the atmosphere. Which of the following best describes what would happen to the number of moths if measures were introduced to reduce air pollution from year 7? A Increase in dark moths and decrease in light moths B Decrease in dark moths and increase in light moths C Increase in dark moths and increase in light moths D Decrease in dark moths and decrease in light moths 28 38. The table below shows the relationship between planting density and the mass of seed harvested for a cereal crop trial. 4 Mass of seed harvested (grams per square metre) 60 8 86 15 105 32 77 128 21 Planting density (number of plants per square metre) What is the percentage increase in mass of seed harvested as planting density increases from 4 to 14 plants per square metre? A 45% B 75% C 90% D 105% 29 39. The diagram below shows the same sections of matching chromosomes found in four fruit flies, A, C, C and D. The genes shown on the chromosomes can be identified using the following key. Key gene for striped body gene for unstriped body gene for normal antennae gene for abnormal antennae Which fly is homozygous for both genes? 30 40. (a) Organisms vary from one generation to the next. This variation may result from the following factors. A Natural selection B Selective breeding C Environmental impact Copy the table below and use this information to complete the table. (Each letter may be used once, more than once or not at all) Description Factor Produces changes not passed on to future generations Organisms that are better adapted to their surroundings survive and breed Effect of the surroundings on the final appearance of offspring Desirable characteristics chosen to produce improved offspring (b) Arrange the following stages of genetic engineering in the correct order. The first stage has been given. Stage number 1 2 3 4 5 Description of stage Bacterial cell produces insulin Insulin gene inserted into plasmid Plasmid removed from bacterial cell Plasmid inserted into bacterial cell Insulin gene removed from human chromosome (c) Give one advantage of genetic engineering. 31 40. Contd. (d) The desert plant shown below has adaptations to survive in dry conditions. Spines Fleshy stem Shallow widespread root system From the diagram give one adaptation which reduces water loss. 32 41. The diagram below shows a genetically engineered bacterial cell. gene from another organism bacterial chromosome (a) Name the type of molecule found in a bacterial chromosome. (b) The bacterium was genetically engineered to produce a particular substance. Name one example of a substance which can be produced in this way and describe its use. (c) Genetic engineering can produce new genotypes to provide better organisms for particular functions. Give one advantage and one disadvantage of genetic engineering compared with selective breeding. 33 42. Labelled diagrams may be included where appropriate. Genetic engineering uses bacteria to produce human insulin. Describe the stages involved in this process. 43. Describe the process of natural selection as illustrated by the peppered moth Biston betularia. 44. The diagram below shows the two different forms of the peppered moth Biston betularia on the bark of a tree located in an unpopulated area. Name and describe the process by which the black form of the moth became the most common form in polluted areas of Scotland. 34 45. The diagram below shows some characteristics of two present day breeds of dog which descended from a wolf-like common ancestor. Wolf-like common ancestor • • Husky Good stamina Strong Collie • Very intelligent • Good herding instinct Name and describe the process which humans have used to produce different breeds of dog. 35 46. The maps below show the changes in distribution of the red squirrel in the UK from 1920 to 1990. (a) Describe the change in distribution between 1920 and 1990. (b) Suggest reasons for this change. (c) Discuss the potential impact this could have on biodiversity. 36