B3- Organisation [and the digestive system] 🍔

Question 1

What is a tissue ?

Answer 1

• A tissue is a group of cells, with a similar structure and function

Question 2

What is a tissue?

Answer 2

• A tissue is a group of cells, with a similar structure and function

Question 3

What is an organ?

Answer 3

• An organ is a group of tissues working for a specific function. [e.g- the stomach. The stomach contains muscle tissue + glandular tissue, which releases enzymes]

Question 4

What is an organ system?

Answer 4

• an organ systems is a group of organs, which work together to form organisms.

Question 5

What are the three main nutrients?

Answer 5

• carbohydrates, starch and lipid.

Question 6

What is the role of the mouth?

Answer 6

• the mouth is where food is chewed. Enzymes in the saliva [which are produced by the salivary glands] then begin to digest the starch into smaller molecules.

Question 7

What is the role of the stomach?

Answer 7

• in the stomach, enzymes begin the digestion of proteins.

Question 8

What is the function of the stomach? [3]

Hint: pepsin

Answer 8

• contract muscular walls
• produce pepsin
• produces hydrochloric acid, which kills bacteria (and creates the right pH for pepsin).

Question 9

This is a question about digestive enzymes. What does bile do + where is it stored and made? [3]

Answer 9

• Bile emulsifies lipids; which increases the surface area for lipase enzymes to break them down
• Bile is stored in the gall bladder, though it is made in the liver.

Question 10

Can you tell me a bit about the gall bladder?

Hint: alkaline bile neutralises ____ acid

Answer 10

• stores + releases alkaline bile (which is made in the liver) that neutralises stomach acid.

Question 11

Quick question. What does the bile do again?

Answer 11

• Bile emulsifies lipids; which increases the surface area for lipase enzymes to break them down.

Question 12

What are the adaptations of the small intestine? [3]

Hint: villi- surface area, mantain concentration gradient +single layer of surface cells.

Answer 12

• the interior of the small intestine have villi which massively increase the surface area [for the absorption of molecules]. This means digested food can be absorbed into the bloodstream, much more quickly.
• there are also microvilli, on the surface of villi- this increases the surface area even further.
• villi has a very good blood supply, so the bloodstream rapidly removes the products of digestion. This increases the concentration gradient.
• the villi also has a thin membrane= provides a short diffusion path, as nutrients only have to diffuse a short distance.
• the small intestine is very long, as it has a length of 5m- this provides a very large surface area for the absorption, of the products of digestion.

Question 13

What is the main role of the large intestine

Hint: ‘water’

Answer 13

To absorb water.

Question 14

What does absorption mean?

Hint: absorbing molecules

Answer 14

Absorption- the process of absorbing small food molecules [broken down by digestion] into the body. [the bloodstream]

Question 15

What is digestion?

Answer 15

Digestion- the process of breaking down large food molecules into smaller molecules.

Question 16

What are enzymes ?

Answer 16

• Sometimes known as Biological catalysts, enzymes catalyse [speed up] chemical reactions and are also large protein molecules, which have a groove on their surface called the active site.
• The active site is where the substrate attaches to [substrate- molecule that the enzyme breaks down]

Question 17

What are biological molecules?

Hint: living organisms + molecules found.

Answer 17

Biological molecules- molecules found in living organisms, that are produced by cells.

Question 18

Fill in the gaps: Enzymes are _______, which is also known as __________ to its substrate.

This is because, the substrate must fit perfectly into the active site and this is known as lock and key theory]

Answer 18

• Enzymes are specific, which is also known as complementary to its substrate.
• This is because, the substrate must fit perfectly into the active site and this is known as lock and key theory]

Question 19

State the differences between the models of enzyme action

Hint: lock + key model and induced fit model.

Answer 19

Lock + key model:

• substrate had to perfectly fit into the active site, like a lock and key.

Induced fit model:

• enzymes actually changes shape as it binds to the substrate.
• [In other terms,] the enzyme is complementary to the substrate.

Question 21

What are the two factors that affect enzymes? And explain why these affect enzymes. [6]

Answer 21

1) temperature- if an enzyme is over the ‘optimum temperature, the enzyme will be denatured.

This is because as we increase the temperature, the activity of the enzyme increases [the reaction gets faster]. This is because as the temperature increases, the enzymes and substrate are moving faster= more collisions per second between the substrate and the active site.

• ; at a certain temperature, the enzyme is working at the fastest possible rate [known as the optimum temperature]. At the optimum temperature, there is the maximum frequency of successful collisions between the substrate and the active site.
• But as we increase the temperature past the optimum, then the activity of the enzyme rapidly decreases to zero + [the enzyme is denatured]
• Since at high temperatures, the enzyme molecules vibrate, and the shape of the active site changes.
• Therefore the substrate can no longer perfectly the active site= the reaction won’t be catalysed. [as the active site is denatured]. So the enzyme can no longer catalyse the reaction.

Question 21

What are the two factors that affect enzymes? And explain why these affect enzymes.

Answer 21

2) pH- An extremely high pH will denature the enzyme

• The enzyme has an optimum pH, where the activity is maximum. If we make the pH more acidic/alkaline, the activity drops to zero.
• This is because the active site denatures, if the conditions are too acidic or too alkaline.

Question 22

What is the order for cell organisation?

Hint: 6 steps

Answer 22

1) organelles
2) cells
3) tissues
4) organs
5) organ systems
6) organisms

Question 23

What are enzymes made from?

Hint: amino acids

Answer 23

A large range of amino acids.

Question 24

Enzymes can be reused. TRUE OR FALSE

Answer 24

True- enzymes can be reused.

Question 25

We all need a balanced diet. Explain the three nutrients + two of their roles. [5]

Answer 25

Carbohydrates (usually starchy foods) :

• provide us energy we need to do chemical reactions + move around.

Lipids:

• act as a long-term store of energy
• keep us warm by insulating us
• protect our organs.
  [- can provide energy for chemical reactions).

Proteins:

• for repair
• break down energy if necessary