PLTW Biomedical Science Final Study Guide
UPDATED Exam Questions and
CORRECT Answers
What is a calorie? - CORRECT ANSWER - A unit of heat energy
With our crude calorimeters in class we burned food by lighting it on fire. What chemical
reaction occurs when food is burned? How does this reaction relate to the breakdown of food for
energy in our body? - CORRECT ANSWER - A combustion reaction occurs. The food and
oxygen in the air combine to form carbon dioxide and water molecules and produce lots of
energy. This happens in the body as well, using enzymes to catalyze all of the reactions.
If you burned a sample of food and the temperature of 100g of water in your calorimeter rose
from 20oC to 36oC, how many calories were in the food sample?
Calories = (specific heat of water) x (change in temp of water) x (mass of water) Specific heat of
water = 1 calorie/goC - CORRECT ANSWER - Calories = (1 cal/goC) (16oC) (100g) =
1600 calories
If the food sample you burned above had a mass of 10g before burning and 8g after burning, how
many calories/gram did the food contain? - CORRECT ANSWER - 1600 calories/2g =
800 calories/gram
We are expressing our calories calculated above as chemistry calories. How are food calories
different? - CORRECT ANSWER - 1 food Calorie = 1000 chemistry calories
Which macromolecules -- carbohydrates, proteins or lipids - have the highest calories/gram? -
CORRECT ANSWER - Lipids have the highest: 9 Calories/gram.
In our bodies the food we eat is broken down into its building blocks as it passes through our
digestive system. Answer the following questions about this process:
Where does digestion begin? - CORRECT ANSWER - In the mouth with active chewing
and the enzymes in saliva.
,The enzymes amylase and lipase are found in saliva. Which macromolecules do these enzymes
break down? - CORRECT ANSWER - Amylase breaks down carbohydrates. Lipase
breaks down lipids.
In the stomach, lipase and pepsin are secreted. Which macromolecule does pepsin break down? -
CORRECT ANSWER - Pepsin breaks down proteins.
What substance is made in the liver and stored in the gall bladder? What does it do? - CORRECT
ANSWER - Bile: it helps to dissolve (emulsify) lipids
The duodenum is part of which organ in the digestive system? - CORRECT ANSWER -
The small intestine
Several enzymes are secreted into the duodenum, including trypsin and chymotrypsin. Which
macromolecule do these enzymes break down? - CORRECT ANSWER - Trypsin and
chymotrypsin break down proteins.
Besides digestion in the first part of the small intestine, what is the major role for the rest of the
small intestine? - CORRECT ANSWER - Absorption of nutrients into the bloodstream.
What happens in the large intestine to the remaining digested food? - CORRECT
ANSWER - Water is removed from the food in the large intestine.
The building blocks of the macromolecules are further broken down through the catabolic
pathway in our cells. Answer the following questions about this metabolic pathway:
What is our primary source of energy? What macromolecule does it come from? - CORRECT
ANSWER - Glucose. Glucose comes from starch, a carbohydrate polymer.
What is the end product of the energy producing catabolic pathway? - CORRECT
ANSWER - ATP
, Which of the macromolecules is a last resort energy source (only used when you run out of the
others)? - CORRECT ANSWER - Protein
Describe three differences between Type 1 and Type 2 diabetes: - CORRECT ANSWER -
Type 1: born with it (maybe genetic component), body does not produce insulin, cannot be cured,
must take insulin to control it
Type 2: later onset, due to inability of body to take insulin into cells (can be problems with
insulin receptors), insulin usually not a course of treatment, can often be cured by changes to diet
and exercise.
Define the term hyperglycemia - CORRECT ANSWER - high blood glucose levels
Why would a diabetic become hyperglycemic? - CORRECT ANSWER - Not taking
enough insulin, eating too much (especially carbs) for the insulin level
Define the term hypoglycemia - CORRECT ANSWER - low blood glucose levels
Why would a diabetic become hypoglycemic? - CORRECT ANSWER - If they had taken
too much insulin or not eaten enough for their insulin levels
Osmosis is the movement of water through a semipermeable membrane, like a cell membrane.
What net direction does water flow between body cells and the blood when a diabetic is
hyperglycemic? - CORRECT ANSWER - When hyperglycemic, the blood is more
concentrated than the cells, so water would move out of the cell into the blood.
How might this movement affect blood pressure? - CORRECT ANSWER - This
movement would cause an increase in blood volume, which should result in an increase in blood
pressure.
UPDATED Exam Questions and
CORRECT Answers
What is a calorie? - CORRECT ANSWER - A unit of heat energy
With our crude calorimeters in class we burned food by lighting it on fire. What chemical
reaction occurs when food is burned? How does this reaction relate to the breakdown of food for
energy in our body? - CORRECT ANSWER - A combustion reaction occurs. The food and
oxygen in the air combine to form carbon dioxide and water molecules and produce lots of
energy. This happens in the body as well, using enzymes to catalyze all of the reactions.
If you burned a sample of food and the temperature of 100g of water in your calorimeter rose
from 20oC to 36oC, how many calories were in the food sample?
Calories = (specific heat of water) x (change in temp of water) x (mass of water) Specific heat of
water = 1 calorie/goC - CORRECT ANSWER - Calories = (1 cal/goC) (16oC) (100g) =
1600 calories
If the food sample you burned above had a mass of 10g before burning and 8g after burning, how
many calories/gram did the food contain? - CORRECT ANSWER - 1600 calories/2g =
800 calories/gram
We are expressing our calories calculated above as chemistry calories. How are food calories
different? - CORRECT ANSWER - 1 food Calorie = 1000 chemistry calories
Which macromolecules -- carbohydrates, proteins or lipids - have the highest calories/gram? -
CORRECT ANSWER - Lipids have the highest: 9 Calories/gram.
In our bodies the food we eat is broken down into its building blocks as it passes through our
digestive system. Answer the following questions about this process:
Where does digestion begin? - CORRECT ANSWER - In the mouth with active chewing
and the enzymes in saliva.
,The enzymes amylase and lipase are found in saliva. Which macromolecules do these enzymes
break down? - CORRECT ANSWER - Amylase breaks down carbohydrates. Lipase
breaks down lipids.
In the stomach, lipase and pepsin are secreted. Which macromolecule does pepsin break down? -
CORRECT ANSWER - Pepsin breaks down proteins.
What substance is made in the liver and stored in the gall bladder? What does it do? - CORRECT
ANSWER - Bile: it helps to dissolve (emulsify) lipids
The duodenum is part of which organ in the digestive system? - CORRECT ANSWER -
The small intestine
Several enzymes are secreted into the duodenum, including trypsin and chymotrypsin. Which
macromolecule do these enzymes break down? - CORRECT ANSWER - Trypsin and
chymotrypsin break down proteins.
Besides digestion in the first part of the small intestine, what is the major role for the rest of the
small intestine? - CORRECT ANSWER - Absorption of nutrients into the bloodstream.
What happens in the large intestine to the remaining digested food? - CORRECT
ANSWER - Water is removed from the food in the large intestine.
The building blocks of the macromolecules are further broken down through the catabolic
pathway in our cells. Answer the following questions about this metabolic pathway:
What is our primary source of energy? What macromolecule does it come from? - CORRECT
ANSWER - Glucose. Glucose comes from starch, a carbohydrate polymer.
What is the end product of the energy producing catabolic pathway? - CORRECT
ANSWER - ATP
, Which of the macromolecules is a last resort energy source (only used when you run out of the
others)? - CORRECT ANSWER - Protein
Describe three differences between Type 1 and Type 2 diabetes: - CORRECT ANSWER -
Type 1: born with it (maybe genetic component), body does not produce insulin, cannot be cured,
must take insulin to control it
Type 2: later onset, due to inability of body to take insulin into cells (can be problems with
insulin receptors), insulin usually not a course of treatment, can often be cured by changes to diet
and exercise.
Define the term hyperglycemia - CORRECT ANSWER - high blood glucose levels
Why would a diabetic become hyperglycemic? - CORRECT ANSWER - Not taking
enough insulin, eating too much (especially carbs) for the insulin level
Define the term hypoglycemia - CORRECT ANSWER - low blood glucose levels
Why would a diabetic become hypoglycemic? - CORRECT ANSWER - If they had taken
too much insulin or not eaten enough for their insulin levels
Osmosis is the movement of water through a semipermeable membrane, like a cell membrane.
What net direction does water flow between body cells and the blood when a diabetic is
hyperglycemic? - CORRECT ANSWER - When hyperglycemic, the blood is more
concentrated than the cells, so water would move out of the cell into the blood.
How might this movement affect blood pressure? - CORRECT ANSWER - This
movement would cause an increase in blood volume, which should result in an increase in blood
pressure.
