8.3 Absorption & Assimilation (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
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Define absorption.
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Cards in this collection (23)
Define absorption.
Absorption is the movement of digested food molecules from the digestive system into the blood and lymph.
How is the small intestine (ileum) adapted for absorption?
It is very long and its lining is highly folded with millions of villi, greatly increasing the surface area.
Where are most nutrients absorbed?
In the small intestine.
Define villi.
Villi are the tiny, finger-like projections on the lining of the small intestine that increase the surface area for absorption.
By which three processes can nutrients be absorbed?
Diffusion, osmosis and active transport.
Define microvilli.
Microvilli are folds in the cell membrane of each villus cell that further increase the surface area for absorption.
Which digested nutrients are absorbed into the blood?
Glucose and amino acids.
Why is the wall of a villus only one cell thick?
To give a short diffusion distance, so absorption happens quickly.
Which digested nutrients are absorbed into the lymph?
Fatty acids and glycerol.
What is the role of the blood capillaries in a villus?
They transport glucose and amino acids away from the small intestine in the blood.
Define assimilation.
Assimilation is the movement of digested food molecules from the blood into cells, where they become part of the cells.
Define lacteal.
A lacteal is the central lymph vessel of a villus that transports fatty acids and glycerol away from the small intestine.
Where is most water absorbed?
Most water (around 80%) is absorbed in the small intestine, with the rest absorbed in the colon.
What is the function of the hepatic portal vein?
It carries nutrient-rich blood from the intestines to the liver.
Glucose and amino acids are absorbed into the , while fatty acids and glycerol are absorbed into the lymph.
Glucose and amino acids are absorbed into the blood, while fatty acids and glycerol are absorbed into the lymph.
The tiny, finger-like projections that line the small intestine are called .
The tiny, finger-like projections that line the small intestine are called villi.
Most of the water in the gut is absorbed in the intestine.
Most of the water in the gut is absorbed in the small intestine.
Blood rich in nutrients is carried from the intestine to the by the hepatic portal vein.
Blood rich in nutrients is carried from the intestine to the liver by the hepatic portal vein.
True or False?
Water is absorbed in both the small intestine and the colon.
True.
Water is absorbed in both, but most (around 80%) is absorbed in the small intestine.
True or False?
Villi and microvilli both increase the surface area for absorption.
True.
Villi are large projections of the gut lining, while microvilli are folds in each cell's membrane; together they greatly increase surface area.
True or False?
Assimilation is the movement of digested food from the intestine into the blood.
False.
That describes absorption. Assimilation is the movement of food molecules from the blood into cells, where they are used.
True or False?
The wall of a villus is many cells thick to slow down absorption.
False.
The wall of a villus is only one cell thick, giving a short diffusion distance for fast absorption.
What happens to digested molecules during assimilation?
They pass from the blood into the cells of tissues and organs, where they are used and become part of the cells.
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