UBC BIO 260 Midterm #1 Exam Questions And Correct Answers
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Course
BIOL 260
Institution
BIOL 260
UBC BIO 260 Midterm #1 Exam Questions
And Correct Answers
When do valves open and close, in the cardiac cycl
e? How does electrical signals travel through the heart? - answer
What are the 4 steps in animal digestion? - answer1. Ingestion
2. Digestion
3. Absorption
4. Incorporation into tissu...
UBC BIO 260 Midterm #1 Exam Questions
And Correct Answers
When do valves open and close, in the cardiac cycl
e? How does electrical signals travel through the heart? - answer✔✔
What are the 4 steps in animal digestion? - answer✔✔1. Ingestion
2. Digestion
3. Absorption
4. Incorporation into tissues or elimination
How are carbohydrates digested in the mouth? - answer✔✔By salivary amylase (it digests
polymers to disaccharides)
How are carbohydrates digested in the intestine? - answer✔✔Enzymes secreted by the pancreas
(pancreatic amylase) + enzymes in the intestinal epithelium (breaks down the disaccharides into
monosaccharides)
Why are some carbohydrates difficult to digest? - answer✔✔Cellulose is difficult to digest
because it is a complex polymer and no animal expresses the cellulase enzymes needed to break
the bonds within the molecule
Where is gut bacteria located in different animals? - answer✔✔Hindgut fermenters: Bacteria in
the cecum + colon
Foregut fermenters: (Ruminants) = Bacteria in modified stomach (rumen) and cecum
What is special about foregut foregut fermenters? - answer✔✔They have a modified stomach
and bacteria in the foregut are able to digest cellulose. The bacterial waste products and dead
bacteria are digested in the rest of the intestine and that provides nutrients for the animals
What are some examples of foregut fermenters? - answer✔✔Sloth, Kangaroo, Colobus Monkey,
Sheep and Llama
What are some traits of hindgut fermenters? - answer✔✔Smaller animals = Large cecum and
small colon
What are traits of the human colon? - answer✔✔Bacteria are found in the colon and it's primary
role is water re-absorption
What are the steps of protein digestion? - answer✔✔1. It starts in the stomach where proteins are
partially digested by pepsin and HCl (stomach acid)
2. Further digestion is by enzymes released by the pancreas (happens in the intestine)
3. Final digestion of proteins occurs inside cells of the small intestine (by intracellular peptidase
enzymes)
What are the steps of protein digestion?. When in the enzyme pepsin active? - answer✔✔Only at
low pH, it is released as pepsinogen (which is inactive) but once it reaches low pH it attacks
itself removing the 'masking sequence' which exposes the active site of pepsin and allows it to
digest proteins
What is the stimuli for stomach acid secretion? - answer✔✔1. The sight, smell, taste or thought
of food
2. The presence of food in the stomach
→ This causes the parietal cells to secrete HCl
What do chief cells do? - answer✔✔Produce pepsinogen (pepsin precursor)
Q. What do parietal cells do? - answer✔✔Produce HCl
Q. What is in the anatomy of the stomach? - answer✔✔Gastric pits/gastric glands, chief cells,
parietal cells
What is the mechanism of HCl secretion? - answer✔✔Must move from the parietal cell to the
lumen of the stomach, which means they have to move against a concentration gradient. So they
must use ATP (the proton comes from CO2)
How does the body deal with HCO3- (a base) in the cell? - answer✔✔The HCO3- moves to the
blood vessel and Cl- moves into the parietal cell which then is transported into the lumen
What is acid reflux? - answer✔✔A common condition when the esophageal sphincter does not
close tightly and this allows stomach acid to leak into the esophagus
How does water absorption occur? - answer✔✔Na+ is absorbed by secondary active transport
and water follows passively via a paracellular pathway (between the cells)
Where does water absorption occur? - answer✔✔In the intestine, the colon it is the most
important for water regulation
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