BIO 9th GRADE MIDTERM

  1. What is the difference between a compound light microscope, a scanning electron microscope, and a transmission electron microscope?  What kind of specimens can be seen using each of these microscopes?

Compound light – specimens can be alive, but it doesn’t zoom in as much, it shows real colors (unless stained)

Electron microscopes- specimens must be dead but there is a lot more visible detail, black and white

Scanning – 3-D image of the surface

Transmission – internal view of specimen

  1. How can you determine the total magnification of a specimen viewed with the microscope?

Multiply the magnification of the ocular lens by the magnification of the objective lens.

Chemistry of Life 

  1. Describe a structure of an atom.

Pictured at right 🡪

  1. What is a compound?  How are compounds related to molecules

A compound is a pure substance made of 2 or more elements in a specific ratio

A molecule is a pure substance made of 2 or more atoms (can be same element) in a specific ratio

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  1. What is an element, an atomic number, and atomic mass?

Element – a type of atom determined by the   Atomic Number (number of protons)

Atomic mass- mass of the atom, measured in amus (atomic mass units), sum of \n protons and neutrons

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  1. What are unique properties of water?

Water is polar and it expands when it freezes.

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  1. What are hydrogen bonds?

Weak bonds between a positive pole (with hydrogens) and another molecule with a negative pole – it’s similar to a magnet because it’s simply negative attracts positive. 

  1. Use the structure of a water molecule to explain why it is polar?

Water has equal amounts of protons and neutrons, just the \n electron stay on one side of the molecule. See picture to right 🡪

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  1. What happens to chemical bonds during chemical reactions?

They get broken and reformed between different atoms to form \n new molecules

  1. Describe the role of energy in chemical reactions?

Reactions require an activation energy in order to occur – there must \n be enough energy present to move the molecules around and to form \n new bonds and break old ones.

  1. What are enzymes and how are they important for living things? \n Enzymes are biological catalysts- they lower the activation energy of life’s reactions to allow them to occur at a reasonable pace

  2. What are macromolecules?

Large molecules that are made of subunits (repeating molecules)

  1. What properties of carbon explain carbon’s ability to form many different macromolecules?

Carbon has 4 valence electrons so it can gain up to four electrons via single, double, or triple bonding.

  1. Name 4 groups of organic compounds found in living things?

Proteins, Carbohydrates, Nucleic Acids, and Lipids

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  1. What are the functions of carbohydrates, lipids, nucleic acids, and proteins?

Carbohydrates: Main energy source, plant structure

Proteins: Bones, muscles, cell structure, enzymes

Nucleic Acids: Genetic Storage and Transmission

Lipids: Energy storage, waterproof membranes

  1. What are the monomers of carbohydrates, nucleic acids, and proteins?

Carbohydrates 🡪 Monosaccharide

Nucleic Acids 🡪 Nucleotides

Proteins 🡪 Amino Acids

  1. Explain why proteins are polymers but lipids are not?

Proteins are made of a single type of repeating subunit called monomers (amino acids). Lipids are made up of more than one type of subunit and they are in no particular pattern (glycerol and fatty acids)

  1. What are the three parts of the Cell Theory and who contributed to it?

  • All living organisms are composed of cells

  • Cells are the basic unit of structure and organization of all living things

  • Cells arise only from previously existing cells, with cells passing copies of their genetic material to their daughter cells

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Contributors:

  • Hooke – discovered cells (saw for the first time)
  • Schleiden – all plants are made of cells
  • Schwann – all animals are made of cells
  1. What are the characteristics of living things?
  • Made of cells
  • Reproduce and use energy
  1. Name two structures that all cells have?

Cytoplasm, Cell membrane, ribosomes, DNA/RNA

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  1. How is a cell like a factory?

The organelles all work together for one common goal like parts and workers of a factory work together. Manager= nucleus, ribosome= workers, lysosome=cleanup crew, ER= assembly line, golgi = packaging department, membrane = doors w/ keyed entry, cell wall = factory wall, vacuole = water cooler

  1. What do prokaryotes and eukaryotes have in common?

DNA/RNA, Cytoplasm, cell membrane, ribosomes, cell wall (plants and bacteria)

  1. What structures do eukaryotes have that prokaryotes do not have?

Nucleus, nucleolus, membrane bound organelles (mitochondria, chloroplasts, golgi, ER, etc)

  1. Which organisms are prokaryotes? Eukaryotes?

Prokaryotes are bacteria, Eukaryotes are everything else (Plants, animals, fungi, protists)

  1. Which organelles are unique to plant cells?  Animal cells?

Plant Cells – Cell wall, chloroplast, large central vacuole

Animal Cells - lysosomes

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  1. What are the 2 main types of cell transport? passive transport and active transport

  2. Which of the 2 require energy? active transport

  3. What are the 3 types of passive transport?  diffusion, osmosis, facilitated diffusion How are they different? small molecules move across the cell membrane using diffusion; water (and other solvents) move across the membrane using osmosis; large molecules move through channel proteins to across the cell membrane during facilitated diffusion

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    1. Which direction do molecules move during passive transport? areas of high concentration to areas of low concentration
    2. Define hypertonic, hypotonic, isotonic. hypertonic - describes a solution with a higher concentration of solute than another solution;  hypotonic - describes a solution with a lower concentration of solute than another solution; isotonic describes a solution with an equal concentration of solute when compared to another solution
    3. What would happen to an animal cell placed into a hypertonic solution?  water would leave out of the cell into the solution until equilibrium is reached - this would shrink the cell Why? water moves along/down the concentration gradient (areas of high concentration to areas of low concentration)
    4. What would happen to an animal cell placed into a hypotonic solution? water in the solution would move into the cell -this would cause the cell to swell Why? water moves along/down the concentration gradient (areas of high concentration to areas of low concentration)
    5. Why don’t plant cells burst when placed in a hypotonic solution? plant cells have a cell wall - the cell wall protects the plant by exerting pressure turgor pressure
    6. What happens when 2 solutions reach equilibrium? molecules continue to move in equal amount in both directions to maintain equilibrium

  4. What are the 3 types of active transport? How are they different? ion pumps - use ATP energy to move ions across the cell membrane; exocytosis - moves materials to the outside of cell;  endocytosis - moves materials into the cell

  5. Which direction do ions move during active transport? areas of low concentration to areas of high concentration

  6. What kinds of things would a cell take in by endocytosis?  food/nutrients…

  7. What kinds of things would a cell release by exocytosis? waste/toxins, hormones…

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  1. What are the reactants (starting materials) and products (ending materials) of photosynthesis?

Reactants: 6CO2 + 6H2O + Light (energy) \n Products: 6O2 + C6H12O6

  1. Where does photosynthesis occur (in which organelle)?

Chloroplast

  1. What kind of organisms photosynthesize? Plants and some bacteria
  2. What are the reactants (starting materials) and products (ending materials) of cellular respiration?

Reactants: 6O2 + C6H12O6

Products: 6CO2 + 6H2O + ATP (energy)

  1. Where does cellular respiration occur (in which organelle)?

Cytoplasm and Mitochondria

  1. What kind of organisms respire (use cellular respiration)?

All of them

  1. What do aerobic and anaerobic mean?

Aerobic- Requires oxygen, Anaerobic – does not require oxygen

  1. Do plants need oxygen?  Do animals?

Yes plants need some oxygen to respire (most of which they gain from photosynthesis)

Yes animals need oxygen to respire

  1. Do plants give off carbon dioxide?  Animals?

Plants give off some carbon dioxide (but they use it in photosynthesis)

Animals give off carbon dioxide.

  1. What is the name of the pigment that makes plants green?

Chlorophyll

  1. What is the energy storage molecule that cells use for energy?

ATP

  1. What process do organisms use to store energy?

Photosynthesis

  1. What processes do organisms use to release stored energy?  Which one is more efficient?

Aerobic Cellular Respiration AND fermentation both release energy from glucose, but aerobic is more efficient (30+ATP vs 2 ATP per glucose)

  1. What is the ultimate source of energy in living things?

The sun

  1. Why does photosynthesis happen the most quickly between 0 and 35o C?

That is the optimal temperature for the enzymes involved

  1. What other factors affect the rate of photosynthesis?

Light intensity, Light color, Amount of carbon dioxide

  1. When and why do cells divide?

Divide during mitosis and cytokinesis (after Interphase of the cell cycle) in order for the organism to grow, reproduce, or to heal/replace damaged cells

  1. Name the main events of the cell cycle?

Interphase (G1, S, G2) = preparing for division and normal living

Mitosis and Cytokinesis = Division

  1. What are chromosomes made of?

DNA wrapped around proteins (histones) which bundle into nucleosomes

  1. What is mitosis? a type of cell division that produces clones; utilized by asexual organisms
  2. What types of cells are produced by mitosis? somatic
  3. Mitosis will happen in which three circumstances?  growth, replace cells, repair cells
  4. When does mitosis happen (relative to the events of the cell cycle)? After the cell copies its DNA and completes interphase
  5. Why is mitosis necessary?

So the cell divides before the surface area to volume ratio gets to large or before DNA overload can occur.

  1. How do the chromosomes line up during metaphase of mitosis?

Chromosomes line up at the center of the cell \n \n \n

  1. What happens to chromosomes during anaphase of mitosis?

They are divided in half at the centromere and each sister chromatid is taken to opposite sides of the cell by spindle fibers.

  1. How does cytokinesis differ in plants and animals?

The cell wall prevents plant cells from “pinching off” like animal cells can. So the plant cells have to go through special steps to make a new layer of cell wall before the cytoplasm splits.

  1. How many daughter cells are there at the end of mitosis? Are these daughter cells genetically identical or genetically different? 2; genetically identical
  2. Each daughter cell has how many chromosomes compared to the parent cell?

Daughter cells have the same number and types of chromosomes as the parent cell in mitosis

  1. Your body use a different kind of cell division to make gametes. Name this type of cell division? Why your body us this type of cell division to make gametes? meiosis; to ensure correct number of chromosomes in gametes (divides chromosome number by half) and to provide genetic variation in the DNA of the gametes

  2. Define diploid. Give an example of a diploid cell. cell with 2 copies of every chromosomes (one from each parent); liver cell

  3. Define haploid. Give an example of a haploid cell. cell with 1 copy of every chromosomes (only from one parent); egg cell

  4. How many daughter cells are there at the end of meiosis? Are these daughter cells genetically identical or genetically different? 4; different

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18. What is binary fission? What type of cell/organism uses binary fission? Binary fission

is more similar to [meiosis/mitosis] however there is [NO nucleus to divide/cytoplasm to divide]. Binary fission is similar to mitosis. It is a type of cell division associated with asexual reproduction. Bacteria (prokaryotes) use binary fission to reproduce. During binary fission a single cell splits into two cells.

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  1. What are the four kinds of bases found in DNA?  How do they fit together?

Adenine bonds with Thymine                     Cytosine complements Guanine

  1. Explain how DNA is replicated?

First the DNA is “unzipped” to form two template strands.  DNA polymerase brings in nucleotides that complement the template strand so the result is 2 identical sets of DNA

  1. Where and in what form is eukaryotic DNA found?

DNA is found in the nucleus, usually as chromatin (loose) except for during division

  1. What is chromatin? a chromosome? a chromatid? a gene?

chromatin is a loose/unwound form of DNA; chromosomes are made up of DNA and protein (DNA tightly wrapped around a histone protein) - chromosomes form when it is time for cell division; a gene is a segment of DNA that codes for proteins

  1. What is the role of DNA polymerase?

It creates and proofreads the new strands of DNA during replication

  1. What is the difference between a gene mutation and a chromosomal mutation?

A gene mutation happens to one particular gene (one protein) a chromosomal mutation affects the entire chromosome (many proteins – much more severe).

  1. Describe the different types of mutations.

Insertion = a nucleotide is added

Deletion = a nucleotide is taken out

Substitution = a nucleotide is replaced

9.  Write the new strands of DNA that will be formed when this molecule of DNA replicates: Strand #1  ATTCGGCGAAT

Strand #2  TAAGCCGCTTA

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Replicated DNA:

Strand #1   ATT  CGG CGA

New Strand TAA GCC GCT

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Strand #2 TAA GCC GCT

New Strand  ATT CGG CGA