Sunday, January 24, 2010

Midterm Review Sheets 1,2 and 3 - Solutions!

Review 1 - Scientific Method, Unity & Diversity, Biochemistry

Quick Review:
a) energy
b) the quantity in an experiment that is measured, observed or tested
c1) three fatty acids attached to a glycerol
c2) the process by which molecules are bonded together by the loss of a water molecule
d) calculations are not necessary for a good experiment - the others are essential!
e) speed
them up/lower the activation energy
f) contains more than one element
g1) because it does not contain BOTH carbon and hydrogen
g2) CO2 + H2O --(light)--> C6H12O6 + O2
h) CO2, water and ATP
i) simple sugars
j) it produces its own food
k) kingdom animalia
l) because it serves to warm up the body and return its temperature to normal levels.
m) grasshopper, hawk, mushroom, butterfly - these organisms all obtain food from the environment
n) H (hydrogen), S (Sulphur), and O (oxygen)
o) acidic - if pH is less than 7, solutions are acidic. 7 is neutral, above 7 is basic.

MC Questions:
1. (2)
2. (4)
3. (1)
4. (3)
5. (2) - the handout used in the regular class has a different question with answer (3) of organelle
6. (1)
7. (3)
8. (4)

9. Grasses and shrubs are producers because they make their own food. They do not eat other organisms, so the arrows always point away.

10.
Photosynthesis: Water and carbon dioxide are combined using the energy of light to form glucose and oxygen gas.
Respiration: Glucose and Oxygen are converted through respiration into ATP, with waste products of water and carbon dioxide.

Cellular respiration is essential because it converts the energy in glucose into a form (ATP) that can be used by cells to perform life processes.

Photosynthesis is essential because it allows the Euglena to produce glucose on its own using light energy, allowing it to survive when food is not available.

12.
The experiment lacks a control group that does not use the plant hormone auxin. The student therefore can't compare to determine whether the hormone helps or not.

Brine Shrimp experiment answers:
THe key to questions like these is to make sure you answer ALL parts of the question. Here are suggested answers to each part as given from the actual Regents grading rubric:

• state how many containers to use in the experiment, and describe what would be
added to each container in addition to the eggs [1]

Three containers, each with a different salt concentration (2%, 4%, and 6%), should be used.
— four containers, one with water, the other three with different salt concentrations (2%, 4%, and 6%)
— four containers, a control and the others with 2%, 4%, and 6% salt solution

• state two factors that must be kept constant in all the containers [1]
— temperature of the water
— number of eggs per container
— salt-water level or volume
— size of container
— amount of time

• state what data must be collected during this experiment [1]
— how many eggs hatch in each salt concentration

• state one way to organize the data so that they will be easy to analyze [1]
— arrange the data in a data table or a spreadsheet
— graph the data

• describe a result that would indicate the best salt solution for hatching brine shrimp
eggs [1]
— The solution that has the most eggs hatch is the best one to use.

Review 2 - Cell Structures, Transport, and Diffusion

Warm up questions:
a) ATP
b) chloroplast
c) nuclear envelope or nuclear membrane
d) nucleolus, which is inside the nucleus
e) to receive vesicles of proteins from the ER, and modify or package them to go elsewhere in the cell
f) rough ER contains ribosomes for protein synthesis
g) energy
h) two layers of phospholipids, the polar or hydrophilic "heads" on the outside of the layer, and the non-polar or hydrophobic "tails" pointed into the layer.
i) the concentration of solute in solution A is greater than the solute concentration of solution B
j) it will expand or burst, since water flows into the cell
k) movement from low concentration to high concentration
l) osmosis is diffusion of water across a membrane

Cell parts:
1. vacuole
2. cytoplasm
3. nucleus (and more specifically, the nucleolus)
4. endoplasmic reticulum, or ER
5. mitochondrion
6. cell membrane

Organelle Chart:
nucleus - contains genetic material and separates it from the cytoplasm, also considered the control center. It is in both plant and animal cells.
ribosome - synthesizes proteins using information in messenger RNA. In both plant and animal cells (along with prokaryotes)
vacuole - stores food and water. In both animal and plant cells, though in plant cells, the central vacuole is very large.
cell membrane - controls transport into/out of cell, in BOTH plant and animal cells.
cytoplasm - fluid that dissolves materials in the cell and helps to give the cell shape. In both plant and animal cells.
mitochondria - convert energy in food (glucose) into ATP, which is a form of energy that cells can use to power life processes
endoplasmic reticulum - location of protein and lipid synthesis in the cell, as well as a transport organelle for these molecules to the rest of the cell. The rough ER contains ribosomes, while the smooth ER produces lipids and does not have ribosomes. In both plant and animal cells
cell wall - a rigid structure made of starch (cellulose) that lets water and gases through. Only contained in plant cells
chloroplast - carries out the process of photosynthesis, in plant cells only.

MC Question Answers:
1. (1)
2. (2)
3. (3)
4. (4)
5. (4) - the cell membrane is where molecules enter the organism through diffusion, which is what happens in the lungs with oxygen and the bloodstream.
6. (1) - you can answer this either by recognizing the structure of a chloroplast, OR by recognizing the reaction described as photosynthesis.

7. Your diagram should have the following to get full credit on this question:
  • I (starch indicator) both inside and outside the bag
  • G (glucose) both inside and outside the bag
  • S only on the inside of the bag (starch is too large to pass through the membrane.
The second part of this question asks for what will be observed when starch indicator is in contact with starch - you may remember from class that any indicator changes color when in contact with the chemical it detects. Specifically, iodine turns a blue-black color when in contact with starch. Either answer (color change, or the appearance of a blue-black color) would be acceptable.

10. You should be able to recognize that cell X is an animal cell and cell Y is a plant cell.
In both cases, each structure is given by:
A - cell membrane
B - nucleus
C - mitochondrion

11.
nucleus - coordinates all cell activities, contains genetic material
cell membrane - controls transport into/out of the cell
mitochondrion - converts food into usable energy through cellular respiration

12. Since cell Y is a plant cell, only photosynthesis occurs in cell Y.

Back Page:

a) If salt is added to the cells, water will flow from inside the cell to outside where the water concentration is less. As a result, the cell will shrink, as shown in View B. The correct answer is salt.

b) Water diffuses out of the cells to change their shape. A common mistake is to say that the cell changes shape because the salt diffuses into the cell - this is not true.

c) You just need to draw a picture that shows MORE cells are visible under low power. Under low power, the magnification is lower, so more cells can be seen.

Saturday School Solutions:
1) 4
2) 1
3) 3
4) 2
5) 3
15) 3
30) 4 - this question is at the bottom of the first page, with the numbers cut off.
31) 2
32) 3
34) 3
35) 4
39) 1
40) 2
41) 4
42) 1 - starch molecules are composed of simple sugars bonded together. The diagram shows the starch molecule being broken apart.
43) 3 - enzymes always work best at a specific temperature and pH. When the temperature rises above a maximum temperature, or outside of a specific pH range, the enzyme can change shape and stop working. When the temperature decreases below its optimal temperature, an enzyme doesn't work as well, and the chemical reaction it controls slows down.
47 - 48:














49. 35 degrees - the graph has its maximum at this temperature. (You need the temperature AND a reason for full credit!)

50. Catalase is an enzyme, which is also a protein.

72. The control group is the group of maple seeds with a pH of 5.6, since this is the pH of normal rain. The scientist wants to compare the more acidic water samples with normal rain.

73. The dependent variable is the number of seeds that had germinated (sprouted)

74. If fewer maple seeds sprouted with the lower pH water, this would explain why there would be fewer young maple trees in regions with acid rain.

59. There are many possible correct answers to this, but a few answers that would NOT receive credit. Some examples:
  • digestion is part of nutrition, so it would not be accepted.
  • reproduction is not accepted because it is not involved in homeostasis
  • giving a correct process, but NOT an explanation would not earn any points.
Correct answers:
Transport moves materials in and throughout an organism, allowing it to keep living functions working.
Excretion removes wastes from the organism. This keeps chemical levels within normal levels.

66. Unfortunately, the correct answer was covered up on the handout (sorry!) by Question 75 - the correct (and hidden) answer is "separate components of chemical mixtures"

67. Choice 2 - the starch can't diffuse out of the tube since starch molecules are too big, but the starch indicator CAN diffuse into the bag. This means the starch indicator will turn blue when it diffuses into the tubing.

68. This demonstrates the process of diffusion.

Whew!
That was a lot of work. For some fun, wrap your head around this slug that is photosynthetic:

Don't forget to visit the quizlet site and review your vocabulary! The links are to the right.
I have also added a link to a Living Environment site that is filled with Regents questions for practice.


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