Biology 40S(H) Final Exam Review KEY January 2019

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1 Biology 40S(H) Final Exam Review KEY January 2019 Mrs. Nilmalgoda Name: Exam Date: Review Credit: Mrs. C. Dunford and Mrs. J. Keith

2 Part 1: Genetics Unit 1: Understanding Biological Inheritance Fill-In-The Blanks and Multiple Choice: 1. At the end of meiosis, gametes (haploid/sex cells) are formed. 2. The physical appearance of a trait is called phenotype while the genetic combination (alleles) of an individual is called genotype. 3. A short pea plant (ss) is considered to be homozygous recessive. 4. An individual with the genotype (Tt) would be considered heterozygous. 5. A heterozygous individual shows the dominant trait in their phenotype, but carries the recessive trait in their alleles. 6. A homozygous individual has two identical alleles for a specific trait. 7. During what phase of meiosis do sister chromatids separate? Anaphase II 8. During what phase of meiosis do homologous chromosomes crossover? Metaphase I 9. Recessive traits only appear when an organism is homozygous. 10. A dihybrid cross between two heterozygous parents produces a phenotypic ratio of: a. 3:1 b. 9:3:3:1 c. 1:2:1 d. 1:6:9 11. The expected genotypic ratio for two heterozygous parents (one trait) should be: a. 1:1 b. 3:1 c. 1:3:1 d. 1:2:1 12. During meiosis, each gamete receives either the allele inherited from the mother or the allele inherited from the father, which illustrated Mendel s Law of Segregation. 13. Genes of different traits are inherited separately of each other, which illustrates Mendel's Law of Independent Assortment. 14. Mendel s Law of Dominance states that the dominant trait will hide or mask the expression of other traits. 2

3 15. A trait that is hidden in the heterozygous condition is said to be a recessive trait. 16. An organism that has two different alleles for a trait is called heterozygous. 17. If a species normally has 46 chromosomes, the haploid cells it produces by meiosis will each have 23 chromosomes. 18. Metaphase I of meiosis occurs when homologous chromosomes line up next to each other at the cell's equator. 19. In the F1 generation of Mendel's experiments (with a homozygous dominant parent and a homozygous recessive parent), the homozygous trait disappeared, only to reappear in the next generation. 20. A cell that has successfully completed meiosis has a chromosome number called haploid. 21. Meiosis results in the production of gametes/sex cells/haploid cells. 22. If genes must be inherited together during meiosis they are said to be linked. 23. The sex of the offspring is determined by the Y chromosome. 24. The 22 pairs of matching homologous chromosomes that do not contain sex genes are called autosomes. 25. The two chromosomes which determine the gender of an individual are called the sex chromosomes (X and Y). 26. Traits controlled by genes located on sex chromosomes are called sex-linked traits. 27. Polygenic inheritance is the inheritance pattern of a trait that is controlled by two or more genes (e.g. skin colour). 28. The ABO blood group is an example of a single gene that has multiple alleles in humans. 29. The process (during meiosis) that can result in Down Syndrome is called non-disjunction. 30. When a gamete with an extra chromosome is fertilized by a normal gamete, a zygote with an extra chromosome is formed. This condition is called trisomy. (ex. Trisomy 21 is Down Syndrome.) 31. A photograph of chromosomes arranged by size and position of centromere is called a karyotype. 32. A graphical representation of genetic inheritance that shows the presence or absence of a particular trait in each member of each generation is called a pedigree. 3

4 Unit 2: Mechanisms of Inheritance Fill-In-The Blanks: 1. A segment of DNA that codes for a specific protein is called a gene. 2. The bonds between nitrogen bases (holding 2 single stranded pieces of DNA together) are called Hydrogen bonds. 3. The structure of a DNA molecule is described as a double-helix. 4. The 3 components (parts) of a nucleotide are nitrogenous base, phosphate group, and a deoxyribose or ribose sugar. 5. There are 4 different nitrogenous bases that are used to build a DNA molecule. They are: adenine, thymine, guanine, and cytosine. 6. DNA Replication is a process by which DNA makes an exact copy of itself. This takes place during interphase of the cell cycle, prior to mitosis or meiosis. 7. If a DNA molecule has 30% adenine, it has 20 % guanine. 8. Transcription occurs in the nucleus, whereas translation occurs at the ribosome. 9. The sequence of protein production is DNA to RNA in the nucleus, then RNA to polypeptide chain/protein in the cytoplasm (at the ribosome). 10. DNA Helicase is the enzyme that unwinds DNA during replication. New strands of DNA are made using the enzyme DNA Polymerase, and DNA Ligase is the enzyme that connects the short segments of nucleotides in a newly made DNA strand. 11. An example of a chromosomal mutation where part of one chromosome breaks off and is added to another chromosome is called translocation. 12. A factor that causes a change in the DNA is called a mutagen, which includes such things as radiation, chemicals, and even high temperature. If this factor is cancer causing, we call it a carcinogen. 13. Endonucleases (or restriction enzymes) are enzymes that cut DNA at a specific nucleotide sequence. Those that make a straight cut leave a blunt (flush) end and those that make a jagged cut leave a sticky (cohesive) end. 14. Technique used to separate and analyze fragments of DNA is called gel electrophoresis. This technique is often used in forensic science to analyze DNA from a crime scene. 15. The pattern of bands created by gel electrophoresis of an individual s DNA is called a DNA fingerprint. 4

5 Part 2: Biodiversity Unit 3: Evolutionary Theory and Biodiversity Fill-In-The Blanks: 1. The gene pool is the total number of alleles in a population. It s said that evolution has occurred if there is a change in allelic frequency within the gene pool. 2. Differences among individuals in a population are referred to as variation among a population. 3. Overproduction occurs when more individuals are born than can be supported in an environment. 4. Extinction is the disappearance of an entire population from the Earth. 5. Charles Darwin proposed a theory of evolution by mechanism of natural selection (also known as survival of the fittest). 6. These two scientists (Hardy and Weinberg) summed up their proposed principle by the formula: p 2 + 2pq + q 2 = The process of forming new species is called speciation. 8. Wisdom teeth are examples of vestigial structures in humans, because they no longer have a purpose. 9. Through convergent evolution, unrelated species in similar environments evolve similar body functions from dissimilar underlying structures, called analogous structures. Conversely, through divergent evolution, closely related species living in dissimilar environments evolve dissimilar body functions from similar underlying structures, called homologous. 10. Artificial seelction selection, the breeding of domestic organisms such as dogs to produce specific desired features, demonstrates that organisms may be modified by controlled breeding. 11. An adaptation is a trait that helps an organism survive and reproduce in a particular environment. 12. Genetic drift is the change in allele frequencies of a small population purely by chance. 13. When disruptive selection (a type of natural selection) occurs, both extremes are favoured over the average phenotype (trait). 14. Charles Darwin wrote his theory of natural selection in a book called On the Origin of Species in The Founder Effect occurs when an isolated population is founded by a small number of individuals. This population may develop allele frequencies that are very different from those of the parent population. 5

6 16. The Bottleneck Effect occurs due to a large natural disaster or overhunting, and causes a dramatic decrease in a population which leads to a dramatic decrease in allele frequency. 17. Under certain conditions*, allele and genotype frequencies in a population will remain constant over time. This is called equilibrium and is represented by the Hardy-Weinberg principle. *Conditions (5): large breeding population, random mating, no mutations, no gene flow between populations, and no natural selection. 18. The total of all alleles of all genes in the population is called the gene pool. 19. We know that African lions and Asian tigers are different species because they have different physical characteristics but more importantly, they show reproductive isolation since they don t try to interbreed in nature or even in zoos. 20. Since both lions and tigers are mammals and cats, how could speciation have occurred in such closely related organisms? When a single group of organisms, like mammals, gives rise to many closely related species, it s called adaptive radiation. In the case of lions and tigers, first there was geographic isolation since they evolved in different parts of the world, leading to allopatric speciation. And even if they lived for a time in the same general area, there would have been ecological isolation (also known as niche differentiation) since they would occupy different habitats, leading to sympatric speciation. Unit 4: Organizing Biodiversity Multiple Choice and Fill in the Blanks: 8. The largest taxonomic level is domain. 9. A dichotomous key or biological key is used to differentiate between similar organisms. 10. The next taxonomic level below the kingdom is called phylum. 11. The animal kingdom is in the domain Eukarya. 12. A group of organisms that are mostly unicellular, have membrane bound organelles, and contain chloroplasts are called: algae/euglenoids. 13. The simplest animals are found in the phylum and an example is a. 6