Bio B & Physics A

Question 1

Mouth/Salivary Glands

Answer 1

-Where mechanical digestion takes place - teeth chew food to break it into smaller pieces and increase it’s SA:Vol ratio
-Salivary glands produce saliva-amylase

Question 2

Oesophagus

Answer 2

-Tube that connects the mouth to the stomach.
-Next to Trachea, smooth muscle
-Peristalsis-Wave-like contractions will take place to push the food molecules down without relying on gravity/Contracting motion of the muscle that squeezes food down

Question 3

Stomach

Answer 3

-Food is mechanically digested by churning actions, via muscle contraction, while enzymes (Protease) start to chemically digest proteins.
-The stomach does not aid breakdown of food
-Hydrochloric acid (HCl) kills harmful microbes and provides optimum pH for correct functioning of protease enzymes

Question 4

Small Intestine

Answer 4

-pH is slightly alkaline (pancreatic juice)
-pancreatic juice raises pH of fluids coming out of the stomach
-Absorption of food molecules through chemical digestion
-Here food is absorbed into blood by diffusion
-Bile emulsifies fats-allows fats and water to mix
-No bile –> No absorption of lipids
-Digestive juices from pancreas added to make more liquid for easy absorption into blood stream
-Ileum is long and lined with villi to increase the SA over which absorption can take place.
-Enzymes are added

Question 5

Large Intestine

Answer 5

-Water is reabsorbed from remaining material (to make it more solid) in the colon to produce faeces

Question 6

Rectum

Answer 6

-Faeces are stored here and released through the anus.
-Faeces contains undigested food, bacteria, dead calls

Question 7

Process-Rectum and Anus

Answer 7

Once rectum reaches max point of storage - brain sends message - anus relaxes muscle contraction that keeps it closed - faeces released (egestion)

Question 8

Pancreas

Answer 8

-produces all 3 types of enzymes
-secretes enzymes in an alkaline fluid into Small intestine to raise pH of fluid coming from stomach–pancreatic juice

Question 9

Liver

Answer 9

-produces bile to emulsify fats - mechanical digestion
-unused amino acids broken down here to produce urea
-stores carbs as glycogen

Question 10

Gall Bladder

Answer 10

stores bile

Question 11

Assimilation

Answer 11

-The movement of digested food molecules into the cells of the body where they are used
-The process of absorption of vitamins, minerals and other chemicals from food –> digestion + absorption

Question 12

ingestion

Answer 12

eating/to take in

Question 13

digestion

Answer 13

breakdown of large molecules into smaller molecules

Question 14

Enzymes

Answer 14

-Enzymes are biological catalysts - they speed up the rate of chemical reaction without being used up or changed in the reaction
-They code for protein - a long chain of amino acids are folded to produce a molecule with a specific shape (active site
-Different enzymes catalyse specific types of reactions

Question 15

What are enzymes involved in?

Answer 15

-Building large molecules from smaller ones
-changing one molecule into another
-large molecules into smaller molecules

Question 16

How does an enzyme work?

Answer 16

-A substrate is a molecule that an enzyme acts on
-A specific substrate (reactant) fits into the active site of a specific enzyme (like a lock and key)
-once in place the substrate and the enzyme bind together. the products afre released from the surface of the enzyme

Question 17

When does an enzyme stop working?

Answer 17

-If the shape of the active site has been changed in any way then the enzyme has denatured and can no longer catalyse reactions as the substrate is no longer complementary
-high temperatures and an unsuitable pH past the enzyme’s optimum can cause it to become denatured.

Question 18

Physical digestion

Answer 18

-digestion of large molecules where there are structural changes but no chemical changes