PLTW Biomedical Science Final Study
Guide Questions and Answers 100%
Pass
What is a calorie? - ✔✔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? - ✔✔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 - ✔✔Calories = (1 cal/goC) (16oC) (100g) = 1600 calories
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,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? - ✔✔1600 calories/2g = 800
calories/gram
We are expressing our calories calculated above as chemistry calories. How are food
calories different? - ✔✔1 food Calorie = 1000 chemistry calories
Which macromolecules -- carbohydrates, proteins or lipids - have the highest
calories/gram? - ✔✔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? - ✔✔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? - ✔✔Amylase breaks down carbohydrates. Lipase breaks down
lipids.
In the stomach, lipase and pepsin are secreted. Which macromolecule does pepsin break
down? - ✔✔Pepsin breaks down proteins.
What substance is made in the liver and stored in the gall bladder? What does it do? -
✔✔Bile: it helps to dissolve (emulsify) lipids
Brittie Donald, All Rights Reserved © 2025 2
, The duodenum is part of which organ in the digestive system? - ✔✔The small intestine
Several enzymes are secreted into the duodenum, including trypsin and chymotrypsin.
Which macromolecule do these enzymes break down? - ✔✔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? - ✔✔Absorption of nutrients into the bloodstream.
What happens in the large intestine to the remaining digested food? - ✔✔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? -
✔✔Glucose. Glucose comes from starch, a carbohydrate polymer.
What is the end product of the energy producing catabolic pathway? - ✔✔ATP
Which of the macromolecules is a last resort energy source (only used when you run
out of the others)? - ✔✔Protein
Brittie Donald, All Rights Reserved © 2025 3
Guide Questions and Answers 100%
Pass
What is a calorie? - ✔✔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? - ✔✔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 - ✔✔Calories = (1 cal/goC) (16oC) (100g) = 1600 calories
Brittie Donald, All Rights Reserved © 2025 1
,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? - ✔✔1600 calories/2g = 800
calories/gram
We are expressing our calories calculated above as chemistry calories. How are food
calories different? - ✔✔1 food Calorie = 1000 chemistry calories
Which macromolecules -- carbohydrates, proteins or lipids - have the highest
calories/gram? - ✔✔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? - ✔✔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? - ✔✔Amylase breaks down carbohydrates. Lipase breaks down
lipids.
In the stomach, lipase and pepsin are secreted. Which macromolecule does pepsin break
down? - ✔✔Pepsin breaks down proteins.
What substance is made in the liver and stored in the gall bladder? What does it do? -
✔✔Bile: it helps to dissolve (emulsify) lipids
Brittie Donald, All Rights Reserved © 2025 2
, The duodenum is part of which organ in the digestive system? - ✔✔The small intestine
Several enzymes are secreted into the duodenum, including trypsin and chymotrypsin.
Which macromolecule do these enzymes break down? - ✔✔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? - ✔✔Absorption of nutrients into the bloodstream.
What happens in the large intestine to the remaining digested food? - ✔✔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? -
✔✔Glucose. Glucose comes from starch, a carbohydrate polymer.
What is the end product of the energy producing catabolic pathway? - ✔✔ATP
Which of the macromolecules is a last resort energy source (only used when you run
out of the others)? - ✔✔Protein
Brittie Donald, All Rights Reserved © 2025 3
