Year 10 Biology Genetics Revision Booklet NAME: Year 10 Biology As this booklet covers the topic of genetics if you fail the SAC, but have fully completed this booklet with adequate detail it can be used to pass you on the outcome if needed. Use the listed words to complete the sentences below. amino chromosomes diploid dominant errors forensic gametes generation genetics genotypes guanine helix identical meiosis nitrogen opposite physical replicate two 1... The ........................ of cells contains genes made of DNA. 2... Genes determine many ........................... characteristics (e.g. eye colour). 3... Diploid human cells contain 23 chromosomal pairs. ......................... cells, however, contain only 23 chromosomes. 4... In a DNA molecule the number of thymine and adenine bases are always the same, and the amount of cytosine and ....................... bases are always the same. 5... The Watson–Crick DNA model is a double ...................... like a twisted ladder. 6... Each step of the DNA helix is made up of two ........................... bases and the bases are attached to the sugar units that are part of the sides of the ladder. 7... The steps of the DNA helix are composed of paired nitrogen bases. There is always an adenine base ........................ a thymine base and a cytosine base opposite a guanine base. 8... Polypeptides are made up of units called ............................ acids. A set of three DNA bases codes for a particular amino acid. 9... During cell division (mitosis) the DNA needs to ............................... to ensure the new cells have identical copies of the DNA. Year 10 Biology 10... In most instances the DNA is copied exactly during mitosis. In some cases ........................ occur and mutations result.I 11... Gametes are formed by a type of cell division called .......................................... 12... The fertilised egg has a ...................... number of chromosomes. 13... X and Y are the sex chromosomes. Females have ................... X chromosomes and males have an X and a Y chromosome. 14... Different forms of a gene are called alleles. Alleles can be ............................... or recessive. Two copies of a recessive gene are required for the characteristic to be expressed. 15... Gregor Mendel was an Austrian monk who conducted the first quantitative .......................... experiments using garden peas. 16... Punnett squares are useful tools to predict the proportion of .......................... and phenotypes in the offspring. 17... Pedigree diagrams are useful in showing how various genes are transferred from one ......................... to another. Draw the basic structure of a nucleotide in the space below. Clearly label each of the components 1. Distinguish between the following pairs of terms. You may wish to use symbols, visual thinking tools or diagrams in your responses. a. Inheritance and genetics ____________________________________________________ ________________________________________________________________________ b. Genotype and phenotype ___________________________________________________ ________________________________________________________________________ c. Chromosomes and gametes _________________________________________________ ________________________________________________________________________ d. Fertilisation and zygote _____________________________________________________ ________________________________________________________________________ e. Genes and alleles _________________________________________________________ ________________________________________________________________________ Year 10 Biology f. Dominant trait and recessive trait _____________________________________________ ________________________________________________________________________ g. Homozygous and heterozygous ______________________________________________ ________________________________________________________________________ h. Homozygous dominant and homozygous recessive ______________________________ ________________________________________________________________________ i. Carrier and recessive trait ___________________________________________________ ________________________________________________________________________ j. Dominance and codominance _______________________________________________ ________________________________________________________________________ k. Maternal and paternal chromosomes __________________________________________ ________________________________________________________________________ l. Pure breeding and hybrid ___________________________________________________ ________________________________________________________________________ 2. For the DNA code TAC CAT CGG CCA ATG ACG CGG CGG ATT suggest the mRNA ____________________________________________ amino acids it codes for. __________________________________________ 3. Name the process by which DNA makes copies of itself. _________________________________ 4. Describe the difference between the phenotypes of a heterozygous individual ____________________________________________________________________________ ____________________________________________________________________________ ___________________________________________________________________________ 5. State the key difference between autosomal inheritance and sex-linked inheritance. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 6. Identify an inherited disorder that is: a. autosomal dominant _______________________________________________________ b. autosomal recessive. ______________________________________________________ Year 10 Biology Analysis Questions Question 1: The following questions refer to figures A and B below. Carefully observe the karyotypes A and B below. Suggest the gender of the individual in A and in B. Justify your responses _____________________________________________________________________________ _____________________________________________________________________________ __________________________________________________________________________ Use your observations and suggest which type of chromosome change is shown in each figure ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ suggest the name of the resulting genetic disorders. ______________________________ ________________________________________________________________________ One of these disorders is also sometimes described as trisomy 21. Suggest a reason for this description ___________________________________________________________ ________________________________________________________________________ Suggest why karyotyping can be carried out only on cells that are about to divide _______ _____________________________________________________________________________ ___________________________________________________________________ A. B. Year 10 Biology Question 2: Different genetic instructions within and between species are due to different nucleotide sequences in their genes. The table below shows part of the sequences of different genes from various organisms. Type of organism Section of gene sequence Duck TAG GGG TTG CAA TTC AGC ATA GGG ATC Human TTG TGG TTG CTT TTC ACC ATT GGG TTC Bacteria AAT GAA TGT AAC AGG GTT GAA TTA AAA Suggest how they are similar. _____________________________________________________________________________ Suggest how they are different. _____________________________________________________________________________ Suggest a reason why they all use the same letters in their genetic coding system. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Year 10 Biology Question 3: Refer to the Davis family tree diagram below to answer the following questions. a.Could the parents of the Davis family, Ken and Margaret, ever have offspring with blue eyes? Explain your answer. _____________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ b.Suggest why all of Geoff and Linda’s children do not have blue eyes. ______________________________________________________________________________ ______________________________________________________________________________ Question 5: Predict the probabilities of the phenotypes and genotypes of the offspring of: a.a homozygous brown-eyed parent and a blue-eyed parent ______________________________________________________________________________ ______________________________________________________________________________ b.two parents heterozygous for brown eyes. ______________________________________________________________________________ ______________________________________________________________________________ Year 10 Biology Question 6: Refer to Chris and Heather’s family pedigree chart and information on their inheritance of colour blindness. a.State the genotype for: Chris Heather b.State the phenotype for: Chris Heather c. What is the chance of: Graeme having colour blindness? Peter having colour blindness? Angela having colour blindness? d.Is it possible for Peter to have a child who is colorblind? Explain. ____________________ ______________________________________________________________________________ ______________________________________________________________________________ Year 10 Biology Question 10: Refer to the pedigree of the family in the diagram below. The inheritance of broad lips (B; unshaded individuals) is dominant to the inheritance of thin lips (b; shaded individuals). a. b. c. d. e. f. How many females are shown in the pedigree chart? __________________________ How many males are shown in the pedigree chart? _____________________ How many females have the thin lips trait? _______________________________ Suggest the genotype of Maggy’s parents. ________________________________ Suggest how Maggy inherited thin lips, when her parents did not. _______________________________________________________________________ _______________________________________________________________________ Suggest the genotypes of a. Peter _________________________________________________________ b. Kurt ____________________________________________________________ c. George ________________________________________________________ d. Rebecca ___________________________________________________ Question 11. The pedigree below traces the recessive trait of albinism in a family. The shaded individuals lack pigmentation and are described as being albinos. a. List any observations from the pedigree that support albinism being a recessive trait. _______________________________________________________________________ _______________________________________________________________________ b. If the albinism allele was represented as n and normal skin pigmentation as N, state the possible genotypes for each of the individuals in the pedigree. _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ Year 10 Biology Question 12: Use the dominant and recessive table below and Punnett squares to assist you in answering the following questions. Dominant trait 1. 2. 3. 4. Recessive trait Free ear lobes Attached ear lobes Mid-digital hair present Mid-digital hair absent Normal skin pigmentation Pigmentation lacking (albinism) Non-red hair Red hair Rhesus-positive (Rh +ve) blood Rhesus-negative (Rh –ve) blood Dwarf stature (achondroplasia) Average stature Widow’s peak Straight hairline Find the probability of Sally (who is homozygous for dwarf stature) and Tom (who has average stature) having a child with dwarf stature. _____________________________________________________________________ _____________________________________________________________________ Find the probability of Fred (who is heterozygous for dwarf stature) and Susy (who has average stature) having a child with dwarf stature. _____________________________________________________________________ _____________________________________________________________________ What is the chance of two parents who are both heterozygous for free ear lobes having a child with attached earlobes? _____________________________________________________________________ _____________________________________________________________________ Michael is heterozygous for mid-digital hair, whereas Debbie does not have mid-digital hair. What is the chance of their children having mid-digital hair? _____________________________________________________________________ _____________________________________________________________________ Year 10 Biology GENETICS CROSSWORD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19 18 20 21 22 23 Across Down Year 10 Biology 2... Division that produces gametes 4... Observable characteristic of an organism 6... Cells containing pairs of chromosomes 8... A gene that needs only one copy to be expressed 12... A different form of a gene 13... Two copies of the same allele 16... Present in a base 18... Male chromosomes 19... One copy of each chromosome 21... Backbone molecule 23... Pairs with cytosine 1... Genetically identical to the parent 2... DNA change 3... Genetic makeup of an individual 4... Genetic square to predict outcomes of crosses 5... Pairs with thymine 7... One of each type of allele is present 9... Chromosomes found here 10... A gene that needs two copies to be expressed 11... Sorting chromosomes 14... Cell division producing identical cells 15... Genetic material 17... Sex cell 20... Genetic syndrome 22... Inherited characteristic