Digestion and how nutrients reach the blood

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Ari eats a slice of bread. Salivary amylase starts breaking the starch in the mouth. What happens to that amylase in the stomach?

   • Acid stops it, so starch digestion resumes in the small intestine
   • It is used up in the mouth, so no amylase is left
   • It switches to digesting protein, since one enzyme works on any food
   • It keeps working at the same rate, since acid does not matter to enzymes
2. 2.

   Bo eats a bowl of beans. In what order do enzymes digest the protein in them?

   • Pepsin in the stomach and again in the small intestine, since one enzyme finishes the job
   • Pepsin in the stomach, then trypsin from the pancreas in the small intestine
   • Trypsin in the stomach, then pepsin from the pancreas in the small intestine
   • Lipase in the mouth, then amylase in the stomach
3. 3.

   Esme drinks a glass of milk. Lactase on the small intestine lining splits the milk sugar, lactose. What does it make?

   • Two glucose units, which can be absorbed
   • Fatty acids and monoglycerides, which can be absorbed
   • Glucose and fructose, which can be absorbed
   • Glucose and galactose, which can be absorbed

4. Read this first

   Map (model, not to scale)

   Glucose from rice starts in the small intestine and ends in a muscle cell. The route between the two boxes is marked ?.

5. 4.

   Jun eats a bowl of rice. Glucose from its starch is absorbed. Which route takes the glucose out of the small intestine?

   • Into a lacteal, then the lymph vessels that carry it on to the blood
   • Through the stomach wall into the blood, then to the liver and the body
   • Into a villus capillary, then the hepatic portal vein to the liver
   • Through the large intestine wall into the blood, then to the liver and the body

6. Map (model, not to scale)

   Fatty acids and monoglycerides from nut oil start in the small intestine and end in the bloodstream. The route between the two boxes is marked ?.

7. 5.

   Kira eats a handful of nuts. Long-chain fatty acids and monoglycerides from the oil are absorbed. Which route do they take?

   • Through the stomach wall into the blood, then to the liver
   • Through the large intestine wall into the blood, then to the liver
   • Into a lacteal, then lymph vessels, then the bloodstream
   • Into a villus capillary, then the hepatic portal vein to the liver
8. 6.

   Luz traces the sugars from a banana. Which organ goes in the box marked ?

   • The stomach, where most sugars are absorbed into the blood
   • The gallbladder, which stores the sugars until they are needed
   • The liver, which receives blood from the small intestine
   • The large intestine, where most sugars are absorbed into the blood
9. 7.

   Both tubes began with the same starch and were kept at the same temperature. Milo reads a model starch test. What does the data show about amylase?

   • The amylase in tube 1 is used up after 5 minutes, so starch stops falling
   • Starch rises in tube 1, because amylase makes more starch from sugar
   • Both tubes lose starch, but tube 1 loses it faster and ends lower
   • Amylase lowers starch from 100 to 10; the water-only tube stays at 100
10. 8.

    “A micrometer (µm) is one thousandth of a millimeter (mm)” Pia reads the lining card. Which statement matches it?

    • Villi and microvilli are about the same size and number
    • There are more villi than microvilli per mm², since villi are bigger
    • Villi are smaller than microvilli, and there are more of them per mm²
    • Microvilli are far smaller than villi, but far more numerous per mm²
11. 9.

    Ren asks why the small intestine lining has villi and microvilli. What do they do for absorption?

    • They add surface area, so more nutrients touch absorbing cells
    • They grind food into smaller pieces, so the enzymes work much faster
    • They make bile, which then carries the nutrients into the blood
    • They squeeze water out of the food, so the waste is much drier
12. 10.

    Tala eats cheese. Bile helps lipase digest its fat. Why does lipase work faster with bile?

    • Bile is an enzyme that itself splits the fat into fatty acids and glycerol
    • Bile breaks large fat globules into droplets, so lipase reaches more fat
    • Bile neutralizes the stomach acid, so that lipase can finally reach the fat
    • Chewing already broke the fat into tiny droplets, so bile adds little