7th Grade Life Science Midterm Study Guide Answer Key
Digestive System:
1. Which two organ systems work to break down food and deliver it to the body?
 The digestive system breaks down food.
 The circulatory system delivers it to the body.
2. Trace the path of food through the digestive system starting with the mouth.
Mouth, esophagus, stomach, small intestine, large intestine, rectum.
3. Explain how both chemical and mechanical digestion are both possible in the mouth?
o Mechanical digestion in the mouth is when the teeth grind and crush the food
into smaller pieces.
o Chemical digestion is when enzymes in the saliva begin to break carbohydrates
into sugars since the cracker turned sweet after sitting on the tongue a while.
4. Explain how food gets down the esophagus. What is that process called?
Food goes down the esophagus because muscular contractions called “peristalsis”
squeeze the food down with the help of saliva. We saw this when we could swallow
something upside down.
5. Complete the table below.
Nutrient
Description
Carbohydrate
they give the body energy,
starches and sugars
Protein
they build and repair cells in the
body
Fat
they give the body energy, also
help insulate
Examples
Fruits, vegetables, breads,
cereals, rice, pasta
meats, egg whites, nuts, dairy
products, cheese
butter, red meat, peanuts, oils
6. In which two organs does the digestion of food primarily take place?
The stomach begins the digestion of proteins and mechanical digestion of chyme.
The small intestine has the most chemical digestion with the use of bile and also
absorption.
7. Which nutrient is primarily digested in the stomach?
Protein is digested in the stomach as we saw with the pepsin egg white lab.
8. Where are most of the nutrients absorbed into the bloodstream?
Most nutrients are absorbed into the bloodstream in the small intestine through the
villi.
9. What is the main job of the digestive system?
The digestive system breaks down food so the nutrients can be used by the body.
10. Which organ would most likely be the cause if you are experiencing diarrhea?
The large intestine is most likely the cause of diarrhea since it absorbs mostly water,
it must not be functioning properly since diarrhea is mostly water not solid.
Circulatory System:
11. What is the main job of the circulatory system?
The circulatory system delivers nutrients and oxygen to cells and removes carbon
dioxide and other wastes from cells.
12. Complete the table below.
Blood Vessel
Function
Veins
Carries blood back to the heart, has valves for keeping one way flow
Arteries
Carries blood away from the heart, strong and very thick
Capillaries
Very thin, allows for gas and nutrient exchange
Use the graph to answer the following: (13-15)
13. What is the best way to describe the relationship between area and velocity? In
other words: As area goes up, the velocity…
goes down, this is so the materials can exit the capillaries and go into the cells.
14. Which blood vessel has the highest speed?
The arteries have the blood traveling at the highest speed since it is pumped with
force from the heart.
15. Which blood vessel has the highest blood pressure and velocity?
The blood vessels with the highest blood pressure and velocity is the arteries as the
blood is squeezed forcibly by the heart in order to send it to the whole body.
16. Explain why your heartbeat speeds up as you exercise.
Your heartbeat speeds up as you exercise to get more oxygen into your body and
more carbon dioxide out as muscles are using the oxygen faster and making waste
faster.
Use the graph to answer the questions below: (17-19)
Change in Heart Rate over Time
Y
axis
80
70
60
0
1
2
3
4
5
X axis
17. What do you think starts to happen around the 2 minute mark?
The person starts to exercise because the heart rate begins to increase.
18. How much faster is the heart beating during minute 5 than during minute 1?
It goes from about 55 to 90 or 45 beats per minute.
19.About how many minutes did it take for this person’s heart rate to go from 60 beats per
minute to 80 beats per minute?
It took about 2 minutes for the heart to go from 60 to 80 beats per minute.
20. Where do nutrients leave the bloodstream to enter body cells?
Nutrients leave the bloodstream and enter the body cells through capillaries.
Respiratory System:
20. Explain how the respiratory and circulatory systems work together?
The respiratory system bring oxygen into the body and gets carbon dioxide out of the
body.
The circulatory system is how these materials are transported throughout the body with
exchange at the capillaries and alveoli.
21. List the 3 main parts of the respiratory system.
Diaphragm, Lungs, Trachea
22. Which organ do you breathe out of when you need extra air? Why?
You breathe through your mouth when you need extra air because it increases the
amount of oxygen you can get into your body and the carbon dioxide out.
23. List the correct path of air through the respiratory system.
Nose or Mouth, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli.
24. Which two human body organs work together to make sure oxygen is transported to
other areas of the body?
The lungs and heart work together to get oxygen to the body.
25. What is the main job of the respiratory system?
The main job of the respiratory system is to get oxygen into the body and carbon
dioxide out of the body.
26. Where does the exchange of oxygen and carbon dioxide occur?
The exchange of oxygen and carbon dioxide occurs in the alveoli which are surrounded
by capillaries.
27. Which organ is most likely the cause of coughing up large amounts of mucus and
shortness of breath?
Probably your bronchi are inflamed and full of mucus if you are having shortness of
breath.
Cellular Respiration:
28. What is cellular respiration?
The process where cells use glucose and oxygen to produce energy to use for life
functions as well as wastes of carbon dioxide and water vapor.
29. What does the circulatory system do to help us get energy in our cells?
The circulatory system delivers nutrients and oxygen to our cells so we can get energy.
30. Which body cell do you think would have the most mitochondria? Why?
The muscle cells would have the most mitochondria since they would be doing the most
work regularly and requiring the most constant energy.
31. Write the respiration equation in words?
Glucose + oxygen = ENERGY + carbon dioxide + water (vapor)
32. Where do the materials of cellular respiration get processed?
The body uses the energy for life functions and the wastes of carbon dioxide and water
vapor are exhaled from the body. It occurs in the mitochondria.
Muscular and Nervous System
33. What is the function of the nervous system? Explain.
The nervous system sends and receives message throughout the body. It allows us to
use our senses to respond to the environment.
34. What does voluntary and involuntary mean? Which muscles go in each category? Explain.
Involuntary means not under our control – smooth and cardiac muscle. We don’t
think about breathing, digesting, or our heart beating.
Voluntary means it is under our control – skeletal muscle we make contract when
we move.
35. How do signals tell your hand to move it away from danger like a flame? Explain.
The sensory neuron sends a signal to the brain that I am touching fire. The brain
sends a signal to my motor neurons in my hand muscles to move away.
Extra Digestive System Graphic Organizer
Organ
Nutrient(s) Digested/Broken
down
Carbohydrates
What nutrient(s) is/are
absorbed?
None
None
None
Protein
None
Small Intestine
Type of Digestion
chemical or mechanical?
Mechanical
Chemical
Muscular contractions/
Mechanical
Mechanical
Chemical
Chemical
Fats, Proteins, Carbohydrates
Large Intestine
None
None
Fats, Proteins, Carbohydrates
some vitamins
Water and Vitamins
Mouth
Esophagus
Stomach