Living Organisms & Genetics Final Exam Review Answers A) Describe the structures and functions of a Euglena. Draw a Euglena. Eyespot Helps the Euglena to detect light so it can move to a bright area to undergo photosynthesis Nucleus Control center of the cell Chloroplast Where photosynthesis occurs Flagellum Tail-like structure that is used for movement Cell Membrane Protective outer layer B) Describe the structures and functions of a Paramecium. Draw a Paramecium. Cilia Small, hair like structures used for movement Contractile vacuole stores waste and other substances and will remove them from the organism. Gullet Acts like the mouth and will move food into vacuoles for storage Oral groove acts like the mouth and directs food into the gullet which moves food into a vacuole. Food vacuole stores food for the organism until it is needed C) Compare the structures and functions of an Amoeba and Volvox. Draw a picture of each organism. Flagella are used for movement Uses chloroplast to undergo photosynthesis and absorbs food through the membrane Reproduces both sexually and asexually Volvox Moves using pseudopodia and uses it to engulf and eat its food. Reproduces both sexually and asexually
D) Construct an animal cell. Label and describe the major organelles: cell membrane, nucleus, mitochondria, and vacuoles. Cell membrane Protects the cell from the surrounding environment Nucleus Controls and directs the functioning of the cell Mitochondria The powerhouse of the cell. Generates energy for the cell Vacuoles Used for storage of food, waste, water, etc. E) Construct a plant cell. Label and describe the major organelles: cell wall, cell membrane, nucleus, chloroplasts, chlorophyll, mitochondria, and vacuoles. Cell Wall Rigid wall to give the plant structure and protection Cell Membrane semi-permeable membrane that will allow substances to pass in and out of the cell Nucleus Control and directs the functioning of the cell Chloroplasts & Chlorophyll Where photosynthesis occurs. Chlorophyll is located inside the chloroplast and is what gives the structure its green color Mitochondria Generates power for the cell Vacuole Storage for water, waste, energy, etc F) Explain the differences between a plant and animal cell give at least three. 1. Outside of the cell Plant cells have a tough outer protective layer call the cell wall. It is rigid and gives the plant structure and protection. The animal cell has a thin, semi-permeable membrane that surrounds the cell. 2. Energy Plant cells have two ways to produce energy for the cell. Its main source is through photosynthesis using the chloroplast. The plant cell will also use the mitochondria as its back up energy source when necessary. Animal cells only have the mitochondria as their main power source. 3. Vacuoles Plant and animal cells both have vacuoles, but the vacuole in the plant cell is much larger than the ones found in the animal cells.
G) Compare and contrast sexual reproduction and asexual reproduction give at least three similarities and differences. Similarities 1. Both allow for continuation of the species Differences 1. Asexual reproduction only requires one parent and sexual reproduction requires two parents 2. Offspring are 100% identical to their parents in asexual reproduction. The offspring are pretty much clones of the parents. With sexual reproduction, the offspring only have 50% in common with each parent. 3. Asexual reproduction occurs most often in unicellular organisms and sexual reproduction happens most often in multi-cellular organisms. H) Explain the process of meiosis Meiosis is a type of cell division that reduces the number of chromosomes in the cell by half to create sex cells for organisms that undergo sexual reproduction. There are two main stages, Meiosis I and Meiosis II. During these stages the chromosomes line up randomly and will separate into new cells. This type of independent assortment with the chromosomes is what gives organisms a lot of genetic variability. I) Explain the process of mitosis. The process of mitosis is used for two main purposes in organisms. First is for growth and development. In multi-cellular organisms, rapid copying of cells adds to the organism allowing it to grow in size. In multi-cellular organisms that have reached maximum growth, mitosis renews and replaces older cells to maintain the organism s size and function.
J) Explain why offspring that result from sexual reproduction have greater variation than offspring that result from asexual reproduction. In asexual reproduction offspring are 100% identical to their parents. They are basically clones of the parent and have the same identical traits and features. With sexual reproduction, the offspring only have 50% in common with each parent. The parents each contribute one chromosome which leads the offspring to look differently than both of the parents. During meiosis (creation of the sex cells) there is a process call independent assortment and crossing over. This allows the parents chromosomes to become even more assorted and will lead to an even greater variation between the offspring. K) Name AND describe two ways of identifying traits in people. 1. Punnett Square This chart is used to help determine the probability that an offspring will have a certain set of genetic traits based on the traits of their parents. 2. Pedigree Chart This chart is similar to a family tree and is used to trace the passing of a certain trait through a family. This will be used to predict the probability that a couple will pass a certain trait on to their offspring. This is most often used to trace genetic disorders. L) Describe the relationship between traits AND heredity Heredity is the passing of traits from parent to offspring. Traits are the genetic characteristics that are passed from parent to offspring. M) Explain the difference between dominant AND recessive traits A dominant trait is the form of the gene that will always show up in an organism if present and working correctly. It is typically represented by the first capital letter of the dominant allele for a trait - Ex.) Seed shape: round (R). The recessive trait is the form of the gene that will only show up if the dominant allele is not present or working correctly. It is typically represented by the lower case letter of the dominant allele for a trait - Ex.) Seed shape: wrinkled (r). N) Explain how genes and alleles are related to genotype and phenotype. Genotype This is the genetic make-up of an organism. It tells you which type of alleles that the offspring has for each specific gene. Example - Gg Phenotype This is the physical appearance of an organism. It tells you how the genes and alleles are being expressed. Example Green pod color O) Explain the difference between heterozygous AND homozygous. Heterozygous This term is used to describe the allele combination that an organism has. Heterozygous means that the organism has two different alleles for the gene. They will have one dominant and one recessive allele for that specific trait. We also use the term hybrid for heterozygous. Homozygous - This term is used to describe the allele combination that an organism has. Homozygous means that the organism has two of the same alleles for the gene. They will have two dominants alleles or two recessive allele for that specific trait. We also use the term purebred for homozygous.
P) Name AND describe two genetic disorders. 1. Albinism This is a recessive disorder where I person has little or no pigmentation in the skin 2. Colorblindness This is a sex-linked disorder that happens most often in men, but can rarely occur in women. The most common form of colorblindness does not allow the person to distinguish between the colors red and green. 3. Down syndrome This occurs when a person receives three copies of the 21 st chromosome instead of the normal two copies. The extra copy causes problems with the way the body and brain develop. It is the most common birth defect in humans. 4. Hemophilia A sex-link disorder that is most common in men and happens rarely in women. This is a clotting disorder where a person s blood clots very slowly or not at all. 5. Marfan s Syndrome A dominant disorder dealing with the connective tissue. This can lead to a person going abnormally tall and having an arm span that is longer than their height. 6. Sickle-Cell Disorder A co-dominant disorder that causes the red blood cells to form in a sickle shape. This can lead to clotting of blood in the body and increase a person s risk for stroke and heart attack. A person with sickle cell or with one sickle cell allele is also immune to malaria. Q) Create and solve a Punnett Square using the alleles: male- GG female- Gg G G G GG GG g Gg Gg R) Explain how the environment and lifestyle choices can impact an organism s survival---give at least three examples. 1. If someone with hemophilia plays contact sports then he is putting himself at risk because if he gets cut or bruised he could heavily bleed and may not be able to get it under control. Hemophilia s have trouble with their blood clotting so putting themselves at risk to get cut or bruised would not be wise. 2. If someone with albinism stays out in the sun then he is putting himself at risk to get sunburn or worse, skin cancer. This is because the person lacks melanin, which helps protect a person from the sun. Albino s should always use sunscreen and wear protective clothing. 3. If a person with sickle cell disease eats a diet high in fats and cholesterol, they are putting themselves at an even higher risk for a heart attack than they already are due to the shape of their red blood cells.
Pedigree Chart: Colored in shape= Black Fur / Non-Colored in shape= White Fur Black Fur White Fur I II A? A? A? III d. Explain why three of I-1 and I-2 offspring had mice with black fur and one with white fur. Black fur is the dominant trait. Three of their offspring received at least one capital B which means that the dominant trait will be the one that is shown. The fourth offspring received two recessive alleles or two lower case letters which allowed the recessive allele to be shown. e. Compare and contrast the two families in the above pedigree chart. The family on the left had more dominant traits in the first two generations than the second family.