ESSAY QUESTIONS KEYED TO THE AP BIOLOGY LABS 

1988:  LABORATORY #2 ENZYME CATALYSIS

	After an enzyme is mixed with its substrate, the amount of product
	formed is determined at 10-second intervals for 1 minute. Data from this
	experiment are shown below.

Time (sec)		0	10	20	30	40	50	60
Product formed (mg) 0.00	0.25	0.50	0.70	0.80	0.85	0.85

	Draw a graph of these data and answer the following questions.
	a. What is the initial rate of this enzymatic reaction?
	b. What is the rate after 50 seconds? Why is it different from the
	    initial rate?
	c. What would be the effect on product formation if the enzyme were
	    heated to a temperature of 100 oC for 10 minutes before repeating
	    the experiment? Why?
	d. How might altering the substrate concentration affect the rate of
	    the reaction? Why?
	e. How might altering the pH affect the rate of reaction? Why?


1989:  LABORATORY #8 POPULATION GENETICS AND EVOLUTION
Do the following with reference to the Hardy-Weinberg model.

a.  Indicate the conditions under which allele frequencies (p and Q) remain 
     constant   from one generation to the next.
b.  Calculate, showing all work, the frequencies of the alleles and frequencies 
     of the genotypes in a population of 100,000 rabbits of which 25,000 are 
     white and 75,000 are agouti. (In rabbits the white color is due to a recessive 
     allele, w, and agouti is due to a dominant allele, W.) 
c.  If the homozygous dominant condition were to become lethal, what would 
     happen to the allelic and genotypic frequencies in the rabbit population after 
     two generations?


















1990:  LABORATORY #5 CELL RESPIRAITON

	The results below are measurements of cumulative oxygen consumption by germinating and dry seeds. Gas volume measurements were corrected for changes in temperature and pressure.

			Cumulative Oxygen Consumed  (mL)
	____________________________________________
	    Time (minutes)	     0	  10        20	 30	 40
	____________________________________________
	22o C Germinating Seeds   0.0  8.8	16.0	23.7	32.0  
		            Dry Seeds   0.0  0.2        0.1	   0.0 	  0.1
	____________________________________________
	10o C Germinating Seeds    0.0 2.9	   6.2	    9.4	 12.5
		            Dry Seeds    0.0 0.0	   0.2	    0.1	   0.2
	____________________________________________

	a.  Using the graph paper provided, plot the results for the germinating 
	     seeds at 22o C and 0o C.
	b.  Calculate the rate of oxygen consumption for the germinating seeds at 
	     22o C, using the time interval between 10 and 20 minutes.
	c.  Account for the differences in oxygen consumption observed between:
		1) germinating seeds at 22o C and at 10o C;
		2) germinating seeds and dry seeds.
	d.  Describe the essential features of an experimental apparatus that could 
	     be used to measure oxygen consumption by a small organism. 
	     Explain why each of these features is necessary.  


























1991:  LABORATORY #9 TRANSPIRATION
	A group of students designed an experiment to measure transpiration rates in a
	particular species of herbaceous plant. Plants were divided into groups and were
	exposed to the following conditions.
 
Group I   -  Room conditions (light, low humidity, 200 C, and little air movement)
Group II  -  Room conditions with increased humidity
Group III -  Room conditions with increased air movement (fan)
Group IV  -  Room conditions with additional light

	The cumulative water loss due to transpiration of water from each plant was measured at 10-minute intervals for 30 minutes. Water loss was expressed as milliliters of water per square centimeter of leaf surface area. The data for all plants in Group I (room conditions) were averaged. The average cumulative water loss by the plants in Group I is presented in the table below.

		Average Cumulative Water Loss by the Plants in Group I

	Time (minutes)	Average Cumulative Water Loss
				(milliliters H2O/centimeter2) 
	    10				3.5  x  10-4
	    20				7.7  x  10-4
	    30			           10.6  x  10-4 	

	a.  Construct and label a graph using the data for Group I. Using the same set of axes, draw and label three additional lines representing the results that you would
predict for Groups II, III, and IV.

	b.  Explain how biological and physical processes are responsible for the differences between each of your predictions and the data for Group I.

	c.  Explain how the concept of water potential is used to account for the movement of water from the plant stem to the atmosphere during transpiration.

1992:	LABORATORY #1 DIFFUSION AND OSMOSIS			       
A laboratory assistant prepared solutions of 0.8 M, 0.6 M, 0.4 M, and 0.2 M sucrose, 
but forgot to label them. After realizing the error, the assistant randomly labeled the
flasks containing these four unknown solutions as flask A, flask B, flask C, and flask D.

Design an experiment, based on the principles of diffusion and osmosis, that the assistant could use to determine which of the flasks contains each of the four unknown solutions.
Include in your answer (a) a description of how you would set up and perform the
experiment; (b) the results you would expect from your experiment; and (c) an
explanation of those results based on the principles involved. (Be sure to clearly
state the principles addressed in your discussion.)







1993:  LABORATORY #10 PHYSIOLOGY OF THE CIRCULATORY SYSTEM

	Many physiological changes occur during exercise.

	(a)  Design a controlled experiment to test the hypothesis that an exercise 
	        session causes short-term increases in heart rate and breathing rate
	        in humans.

	(b)  Explain how at least three organ systems are affected by this increased
	        physical activity and discuss interactions among these systems.

1994:  LABORATORY #2  ENZYME CATALYSIS

Enzymes are biological catalysts.
	a.  Relate the chemical structure of an enzyme to its specificity and catalytic activity.
	b.  Design a quantitative experiment to investigate the influence of pH or temperature
	      on the activity of an enzyme.
	c.  Describe what information concerning the structure of an enzyme could be inferred
		      from your experiment.