Grade 11 Biology Genetics Unit Test

SBI3U Grade 11 Biology Genetics Unit Test Review Questions Biology Genetics Review Questions/ Answers DNA 1) Indicate the importance of DNA in the human body DNA in the body contains important genetic information that teaches the body how to produce the correct proteins for proper human function. Without DNA, the body wouldn’t know how to create cells and therefore bodily functions will not perform. 2) Describe the structure and function of DNA DNAs consists of a Deoxyribose sugar, phosphate backbone, and Nitrogenous base (Guanine, Cytosine, Adenine, Thymine). The Nitrogenous bases create base pairs where Guanine pairs with Cytosine and Adenine pairs with Thymine. The phosphate forms the length of the ladder while the base pairs and deoxyribose forms the steps of the ladder. In general, DNA is a double helix, twisted ladder that is coiled into chromosomes. The function of DNA is to encode genetic information that is essential to creating new organisms, cells, and proteins which will then add up to define new bodily functions. 3) Describe Base Pairs and identify the four bases Base pairs are pairs of nitrogenous bases in the form of AT, CG, TA, and GC. Each nitrogenous base is paired with another nitrogenous to form the steps of the DNA ladder. The sequences of these pairs encode genetic information that is read when the body makes new cells. Each nitrogenous base is unique based on how many rings it has. Adenine and Cytosine are purines with 2 rings. Thymine and Guanine are pyrimidine with 1 ring. Base pairs are as so because these nucleotide pairs must pair up to form 3 rings. Any more and the DNA structure would be obstructed. 4) Identify the 3 components of a DNA Nucleotide Deoxyribose sugar: on the side to hold the base pairs in place Phosphate: holds the sugars and keeps them standing Base Pairs: consisting of nitrogenous bases in the centre attached with hydrogen bondings. 5) Explain the significance of the human genome project The human genome project compiled all 30,000 genes of the body through 3 billion individual characters; a list of all the information that makes up what a human is. This information gathered by the human genome project is significant because it’s the first time that there was a database about a single species in a data form. This allows for comparisons of different human genetic differences, and to analyze the data to find genetic relations to what causes diseases. Having this piece of data will allow us dive deep within the genetic molecular makeup to help develop cures and preventions for certain diseases and to know what makes who we are. Cell Division 1) Distinguish between somatic cells and sex cells (gametes) in terms of location and genetic makeup Somatic cells are cells that form most of an organism’s parts. Somatic cells contain diploid chromosomes, meaning there are pairs of each chromosome within a somatic cell. Contrary to somatic cells, sex cells are located only within reproductive organs such as the testes and ovaries. They are haploid cells where they only contain half the number of chromosomes as there are in a somatic cell. 2) Explain why gametes must be haploid, while somatic cells are diploid Gametes must be haploid because they will be joining the gamete cells from their mates where they will join together to create a child of the same species. Being the same species, they must have the same number of chromosomes. Half the number of chromosomes from each parent will join together to form a full set of chromosome in the child. If gametes were haploid, then the result from sex would be a child with twice the number of normal chromosomes; which won’t happen. Gametes form children with other gametes to increase diversity and variation between traits. On the other hand, somatic cells are diploid because it’s essential for normal somatic cells to keep a backup of their chromosomes in case the main set gets corrupted. Genetic information won’t likely change over a person’s lifetime and it’s important that every cell receives the same information from day 1. 3) Explain the stages of the cell cycle and indicate the main events that occur at each stage The sequence of activities that take place during a cell's life is called the cell cycle. The cell grows and gets ready for synthesis during the G1 phase. The cell can decide whether it wants to start synthesis after G1 phase or go into rest phase. The replication of the cell's DNA then starts during the S (synthesis) phase. The cell completes its growth in the G2 phase and moves into mitosis to begin dividing. 4) State the purpose of mitosis The purpose of mitosis is to create daughter cells that are identical to their parent cell. 1 division leads to 2 cells. This let’s the body expands and creates multiple cells instead of growing a large one. One large cell due to it’s volume vs surface area ratio being higher, the amount of nutrients able to penetrate the cell through diffusion will be obstructed, thus mitosis is used to separate these cells into 2 where each cell can independently keep living. 5) Outline the sequence of steps involved in mitosis and indicate the structures involved in this process Prophase: -chromatin condenses and becomes visible -nuclear membrane begins to break -sister chromatids begin to move to each pole Metaphase: -Spindle fibers attach onto the centromeres of the sister chromatids -Sister chromatids line up in a straight line and face opposite poles -Lines up on the equatorial plane Anaphase: -Centromeres split and move to opposite poles -sister chromatids pulled by spindle fibers Telophase: -nuclear membrane reforms -spindle fibers gone -chromatids back to chromatin, decondenses Cytokinesis: -cytoplasm divides into 2 through a pinching process -2 individual cells formed. -cell wall divides cells in plant cells. 6) State the purpose of meiosis The purpose of meiosis is to produce daughter cells with half the number of chromosomes. They must produce cells with half the number of chromosomes in order to mate with other cells to produce a copy of the same species. Meiosis is the process where cells are duplicated and the result is 4 cells each with half the number of chromosomes. 7) Outline the sequence of steps involved in mitosis and indicate the structures involved Refer to main note 8) Identify the stages of mitosis and meiosis using diagrams Not right now