B3- Organisation [and the digestive system] 🍔 Flashcards
What is a tissue ?
- A tissue is a group of cells, with a similar structure and function
What is a tissue?
- A tissue is a group of cells, with a similar structure and function
What is an organ?
- 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]
What is an organ system?
- an organ systems is a group of organs, which work together to form organisms.
What are the three main nutrients?
- carbohydrates, starch and lipid.
What is the role of the mouth?
- 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.
What is the role of the stomach?
- in the stomach, enzymes begin the digestion of proteins.
What is the function of the stomach? [3]
Hint: pepsin
- contract muscular walls
- produce pepsin
- produces hydrochloric acid, which kills bacteria (and creates the right pH for pepsin).
This is a question about digestive enzymes. What does bile do + where is it stored and made? [3]
- 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.
Can you tell me a bit about the gall bladder?
Hint: alkaline bile neutralises ____ acid
- stores + releases alkaline bile (which is made in the liver) that neutralises stomach acid.
Quick question. What does the bile do again?
- Bile emulsifies lipids; which increases the surface area for lipase enzymes to break them down.
What are the adaptations of the small intestine? [3]
Hint: villi- surface area, mantain concentration gradient +single layer of surface cells.
- 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.
What is the main role of the large intestine
Hint: ‘water’
To absorb water.
What does absorption mean?
Hint: absorbing molecules
Absorption- the process of absorbing small food molecules [broken down by digestion] into the body. [the bloodstream]
What is digestion?
Digestion- the process of breaking down large food molecules into smaller molecules.
What are enzymes ?
- 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]
What are biological molecules?
Hint: living organisms + molecules found.
Biological molecules- molecules found in living organisms, that are produced by cells.
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]
- 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]
State the differences between the models of enzyme action
Hint: lock + key model and induced fit model.
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.
What are the two factors that affect enzymes? And explain why these affect enzymes. [6]
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.
What are the two factors that affect enzymes? And explain why these affect enzymes.
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.
What is the order for cell organisation?
Hint: 6 steps
1) organelles
2) cells
3) tissues
4) organs
5) organ systems
6) organisms
What are enzymes made from?
Hint: amino acids
A large range of amino acids.
Enzymes can be reused. TRUE OR FALSE
True- enzymes can be reused.
We all need a balanced diet. Explain the three nutrients + two of their roles. [5]
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
