Welcome to your Edexcel A2 Biology 1 1. The statement which proves the common ancestry between different species. A species exists as one or more populations. Bacteria are unicellular organisms. All new species arise from an existing species.2. Choose the correct order of formation. Population-ecosystem-community Ecosystem-community-population Population-community-ecosystem Community-population-ecosystem3. Which is not an evidence to indicate the common ancestry shared between different species? The rise of population of different species over time. Common physiological pathways. DNA as the genetic material and 'universal genetic' code. Cell structure4. What is homozygous genotype? Having no alleles. Having 2 different alleles of a gene. Having a combination of 3 alleles of a gene. Having 2 identical alleles of a gene.5. What is a genetic drift? Increase in the variation of phenotypes within a short period of time. Decrease in the variation of phenotypes within a short period of time. Change in allele frequency that occurs by chance. Rapid change in the genotype over a long period of time.6. The presence of 2 genes on the same chromosome so that they tend to be inherited together and do not assort independently. Loci Inheritance Independent assortment Linkage7. How many pairs of autosomes are present in a human being? 22 2 23 98. An example of a sex linked disorder. Cystic fibrosis Albinism Haemophilia Elephantiasis9. Which does not describe the niche of an organism in an ecosystem? Presence of air in the atmosphere Habitat How it interacts with other species How it obtains energy10. Which mechanism(s) allow changes to the pool of genes? a) Natural selection b) Genetic drift c) Speciation d) Gene flow a, b & c All c & d only a, b & d11. Choose the word which is not very closely related to an allele. Phenotype Heterozygous Gene Homozygous12. Select the incorrect statement out of the following. Competition occurs within and between populations for the means of survival. Sexual reproduction produces genetic variation among individuals in a population. Populations of different species live in communities. Populations within communities are affected only by the abiotic (physicochemical) factors in an ecosystem.13. Which is not a factor affecting the carrying capacity of an ecosystem? The effect of abiotic factors Mode of communication of each organism Interspecific and intraspecific competition Predation14. What is heterozygous genotype? Having 2 identical alleles of a gene. Having 2 different alleles of a gene. Having 3 same alleles of a gene. Having no alleles.15. Which of the following is not an evidence for evolution? Antibiotic-resistant bacteria Peppered moths during industrial revolution Fossils Thick fur of polar bears16. Select the incorrect pair out of the following. Phenotype-expression of genotype Allele-gene Population-mutation Genotype-genetic constitution17. Which of the following does not occur if a population becomes isolated from other populations of the same species? No gene flow New species may evolve over time. Organisms in the isolated population may become unable to breed and produce fertile offspring with organisms from other populations. No accumulation of genetic differences in the isolated population.18. Select the incorrect statement regarding ecosystems. A habitat describes the place where a species lives within an ecosystem. Ecosystems are dynamic systems. Ecosystems can range in size from the very small to the very large. A forest ecosystem includes only the community of organisms.19. A change in the allele frequency of a population is ___________. Species Competition Evolution Mutation20. Reasons for variation in the phenotypes of organisms in a population. a) Environmental factors b) Genetic factors c) Unwillingness to change d) Variations in the genotypes b, c & d only a, b & d a & b only All21. Select the incorrect statement out of the following. All new species arise from an existing species. An individual inherits alleles from their own. The theory of evolution underpins modern Biology. The individuals of a species share the same genes but (usually) different combinations of alleles of these genes.22. Select the incorrect statement regarding sex chromosomes. There are 2 types of sex chromosomes. The Y chromosome is much shorter than the X. A person with two X chromosomes is female. They are always homologous.23. Select the incorrect statement regarding alleles. Alleles are passed onto an organism through parent/s. There may be many alleles of a single gene. Alleles are dominant or recessive only. In a diploid organism, the alleles at a specific locus may be either homozygous or heterozygous.24. Which is not a condition for Hardy-Weinburg equilibrium? Population must be very large. No mutations Random mating Natural selection25. Which of the following is an example for human blood groups? Epistasis Sex inheritance Recessive alleles Multiple allelesTime is Up!