BIOLOGY MIDTERM 2016 REVIEW

  1. Which element was absent in the early earth’s atmosphere? (carbon dioxide, Oxygen)

Oxygen

  1. What is homeostasis? Homeostasis is maintaining a stable internal environment.
  2. Calculate the total magnification of a microscope using the following formula:

Total Magnification = magnification of eyepiece x magnification of objective lens

  1. A microscope has an eyepiece lens with a power of 10X. The objective lens being used has a power of 4X.

Total magnification = 40X

  1. A microscope has an eyepiece lens with a power of 10X. The objective lens being used has a power of 40X

Total magnification = 400X

  1. A microscope has an eyepiece lens with a power of 10X. The objective lens being used has a power of 10X.

Total magnification = 100X

Using the information given below to answer questions 4a and 4b.

You are conducting an experiment to determine if increased ultraviolet radiation from the decrease in the ozone layer is killing off frog tadpoles. After examining all of the data available in the library, you decide to go with a hypothesis that increased ultraviolet radiation from the sun is killing off the tadpoles. You design an experiment with a control and an experimental group. Your control group (group 1) involves 100 tadpoles in a five gallon container of water that is covered by glass (knowing that the glass will filter out the ultraviolet radiation). The experimental group (group 2) will be set up exactly like group 1, except that instead of being covered with glass, it is covered with an acrylic Plexiglas, which will not filter out the U.V. radiation. You then place the groups outside for a period of a month, and observe the results.

Result
Group 1 / Group 2
Number of tadpoles started with / 100 / 100
Number of tadpoles finished with / 96 / 96

4a. Identify the independent variable and the dependent variable?

The independent variable is the acrylic plexiglass used to cover the container and dependent variable is the number of tadpoles survived.

4b. Identify the control group and the experimental group?

The control group is the group 1, which was covered with glass and the experimental group was group 2 that was covered by an acrylic plexiglass.

  1. List the functions of cell membranes.
  2. To separate the inside environment of the cell from the outside environment.
  3. To regulate what enters or leaves the cell.
  4. How does active transport differ from passive transport?

In active transport substances are moved across the cell membrane against the concentration gradient using energy whereas in passive transport substances are moved across the membrane from high to low concentration without using energy.

  1. In an experiment, a group of students placed several raisins in a container with 100 milliliters of water. They covered the container and let the raisins sit overnight. The students removed the raisins from the container and observed that they were larger. They also observed that the volume of water in the container had decreased.

Explain why the raisins became larger? Name and describe the process that caused this change in the raisins.

Raisins became larger by gaining water. Since they had low concentration of water inside as compared to the outside environment, water moved from outside (higher conc.) to inside of the raisins. This process is called osmosis in which water molecules move from an area where they are in high concentration to an area of lower concentration across a semi-permeable membrane.

  1. Explain why placing peeled carrots in salty water makes them flaccid while placing them in pure water makes them crisp and crunchy.

Salty water is hypertonic to the environment inside the carrot cells. In hypertonic solution, carrots lose water. This situation is reversed when carrots are placed in pure water because carrots gain water by osmosis when placed in hypotonic environment.

  1. In active transport, molecules are moved against their concentration gradient, whereas in passive transport molecules are moved with the concentration gradient.
  1. What critical role do enzymes play in the living systems? Can an organism function normally if an enzyme is either lacking or is dysfunctional? What could be the cause of a dysfunctional/absence of an enzyme in a living system?

Enzymes are critical for all living things because they catalyze/speed up chemical reactions. An organism cannot function normally without an enzyme or if the enzyme made in the cells is defective/dysfunctional. The main cause of a dysfunctional/absence of an enzyme is a mutation in the gene, which codes for that particular enzyme. Mostly frameshift mutations caused by deletion/insertion or nonsense mutation caused by substitution result in dysfunctional proteins or for the absence of proteins.

  1. True/False: Bacteria are prokaryotic organisms.
  1. Identify the illustrations shown below as prokaryotic bacterial cell, eukaryotic plant cell or eukaryotic animal cell. Circle the cell that can most likely conduct photosynthesis.

Prokaryotic bacterial cell Eukaryotic animal cell

Eukaryotic plant Cell

  1. A cell containing a cell wall, chloroplasts and one/two large central vacuole is a plant cell.
  2. A cell that lacks chloroplasts and a cell wall is an animal cell.
  3. The products of cellular respiration are CO2, H2O and ATP.
  4. Photosynthesis takes place in the chloroplasts of plant cells.
  5. The products of photosynthesis are Glucose/C6H12O6 and Oxygen/O2.
  6. ATP molecules are used by organisms to transfer/store energy.
  7. Oxygen is produced by photosynthesis, which most organisms use to break down glucose to get energy by a process called cellular respiration.
  8. Carbon dioxideis used by photosynthesis, which is produced by heterotrophic organisms during cellular respiration.
  9. True/False: Carbon dioxide concentrations are higher in winter than in summer because the amount of photosynthesis conducted by plants is lower in winter than in summer.
  1. True/False: The amount of O2 production is lower in an area where there are many trees.
  1. Explain why theconcentration of CO2 islower near the tomato fieldsas compared to an area that does not have any plantsduring day time.

The concentration of CO2 is lower near the tomato fields as compared to an area that does not have any plants because plants remove carbon dioxide to use it as a raw material for photosynthesis. They add oxygen via photosynthesis to the environment.

  1. Summarize the process of Cellular respiration and Photosynthesis in chemical equations.

Photosynthesis

6CO2 + 6H2O+ Sunlight C6H12O6 +6O2

Cellular Respiration

C6H12O6 +6O2 6CO2 + 6H2O +ATP

  1. Can photosynthesis and cellular respiration processes be thought of as opposite processes? Why?

Yes, the products of photosynthesis are the reactants of cellular respiration

  1. Why is cellular respiration and photosynthesis important for maintaining life?

Cellular respiration and photosynthesis important for maintaining life. Living things are dependent on plants for food/glucose and oxygen, and they are dependent on cellular respiration for breaking down glucose to obtain energy. Carbon dioxide produced as a result of cellular respiration is used by plants as a reactant for photosynthesis while oxygen produced by plants through photosynthesis is used for cellular respiration to oxidize glucose.

  1. To investigate the processes of photosynthesis and cellular respiration, a group of students sets up an experiment with four flasks as shown.

Flask 1: 100 mL water, 1 mL bromothymol blue, plant

Flask 2: 100 mL water, 1 mL bromothymol blue, 2 small fish

Flask 3: 100 mL water, 1 mL bromothymol blue, plant and 2 fish

Flask 4: 100 mL water, 1 mL bromothymol blue

All four flasks are stoppered and placed under floodlight.

  1. What color would the solution in each flask be after few hours? Indicate which process/processes would take place in each flask.

Flask 1: Blue; photosynthesis

Flask 2: Yellow; cellular respiration

Flask 3: Blue/Yellow; both photosynthesis and cellular respiration

Flask 4: Blue; No change in bromothymol color (blue)

  1. Explain how the processes that have occurred in each flask result in the observed color of the bromothymol blue solutions.

Flask 1: Blue; plants will produce oxygen via photosynthesis, which will not change bromothymol’s color

Flask 2: Yellow; Fish will carry out cellular respiration, as a result of which carbondioxide will be produced. When carbon dioxide is added to bromothymol solution, it makes a weak carbonic acid and changes its blue color to yellow

Flask 3: Blue/Yellow; both photosynthesis and cellular respiration can take place; the color of bromothymol would depend upon the concentration of oxygen /carbon dioxide produced.

Flask 4: Blue; No change in bromothymol color (blue) This is a control set up.

  1. Predict what will happen in each flask if placed in dark for 24 hours.

Since photosynthesis cannot take place in dark, the color of solution in all flasks except for # 4 will change to yellow color due to CO2 produced by plant and fish as a result of cellular respiration.

  1. Organic compounds are composed of Carbon and Hydrogen.
  2. Carbohydrates are organic compounds composed ofCarbon, Hydrogen and Oxygen. ( Carbon, Nitrogen, Oxygen, Hydrogen)
  3. What will be the number of carbon and oxygen atoms in the following carbohydrate?

Cx H24 Ox ______(24, 12, 14)

  1. Disaccharides and polysaccharides are carbohydrates composed of simple sugars or monosaccharides. (simple, complex, carbohydrates)
  2. Carbohydrates in our diet play an important role in our bodies because they provide us with energy. (proteins, energy)
  3. Lipids function as long term energy storage molecules.
  4. Oils, fats and waxes are hydrophobic, meaning they repel water (hydrophilic, hydrophobic).
  5. Oil, fats and waxes are the examples of lipids. (proteins, carbohydrates or lipids)
  6. The monomers that make proteins are amino acids. (monosaccharides, amino acids, nucleotides)
  1. What are enzymes? How do they affect the rate of chemical reactions?

Enzymes are proteins that catalyze/speed up chemical reactions.

  1. List the factors that can affect the enzyme action.
  • Temperature
  • pH
  • substrate/enzyme concentration
  1. The monomers that make proteins are called amino acids, that are linked in a chain, which is folded to make a particular protein molecule.
  2. If a protein was heated it would experience denaturation , which is the loss of shape and function of a protein.
  3. DNA stores genetic informationto make proteins.
  4. The sections of DNA that stores genetic/heredity information to make proteins are called genes.
  5. Summarize the flow of genetic information.

DNA RNA PROTEIN

  1. The monomers that make DNA are called nucleotides.
  2. According to Chargaff’s rule: Adenine = Thymine, Cytosine = Guanine.
  3. True/False. All living things contain DNA in their cells.
  4. A change in a gene/DNA sequence called a mutation can result in a defective protein.
  5. Mutations in DNA/genes give rise to genetic variations in organisms that may help them to survive in a certain environment.
  1. Nucleotides can only be added to the 3’ (OH) end of a DNA strand. Label the 5’ and 3’ ends of each DNA strand?

5’ 3’

3’5’

  1. Draw a labelled structure of a DNA molecule that is 4 nucleotides long in your notebooks.

Practice drawing a DNA molecule that is 4 nucleotides long. Make sure you have all parts labeled: Sugar phosphate backbone, base pairs, hydrogen bonds, nucleotide and 3’ and 5’ ends of each strand of DNA.

  1. Briefly describe how proteins are made in the cells.

Proteins are made in the cells at the ribosomes. This process is called protein synthesis that involves two main steps. The first step –transcription is completed in the nucleus, mRNA is made while transcribing/copying the gene using the template strand of DNA. The second step- translation takes place at the ribosome where mRNA codons are translated into a chain of aminoacids/polypeptide to make a protein.

Use the codon table provided to answer question # 51.

  1. A section of DNA is give below. Determine, from the DNA sequence, what the amino acid sequence of the protein will be.

5’ ATG CGA TAC TGG CTC CTG TAA 3’ Non Template/Gene strand

3’ TAC GCT ATG ACC GAG GAC ATT 5’ Template Strand

5’AUG CGA UAC UGG CUC CUG UAA 3’ mRNA

Met- Arg- Tyr- trp- leu- leu- STOP Amino Acids

STOP is not an amino acid.

  1. A mutation has occurred in the DNA sequence: T-T-A-G-C-C-A-G-A. The sequence is now: T-T-A-C-C-C-A-G-A. What type of mutation has occurred?

Substitution

  1. Individuals with one form of lactose intolerance do not produce the enzyme lactase because the gene coding for the production of lactase is shut off in their cells. Which process does not occur for the gene?

Protein Synthesis

  1. The normal hemoglobin protein consists of 574 amino acids. Approximately how many base pairs (bp) code for this protein?
  1. 191 bp
  2. 1,722 bp
  3. 287 bp
  4. 1,910 bp
  1. To code for a particular protein, a gene consists of 12,669 base pairs. Assuming that 3 base pairs code for the START and 3 base pairs code for STOP, approximately how many amino acids do we anticipate exist within the protein?
  1. 4223 amino acids
  2. 4,222 amino acids
  3. 37,989 amino acids
  4. 38,007 amino acids

Since STOP is not an amino acid, subtract 3 base pairs from 12,669. You must get 12,666 base pairs.Each codon made up of triplet bases codes for one amino acid.

12,666 /3= 4222 amino acids

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