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AQA A Level Biology > MIX > Flashcards

MIX Flashcards

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1
Q

What does ‘explain’ mean?

A

Explain means to not describe it, but answer why or how it happens, give a reason

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2
Q

What does ‘describe’ mean?

A

Describe means to not explain it, but state/outline what it is like in structure, appearance and function.

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3
Q

What is a homologous pair?

A
  1. A homologous pair is pair of chromosomes that have the same structure (with the same genes at the same loci), but different alleles
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4
Q

Millimetres to micrometers

A

x10^3

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5
Q

Magnification =

A

(image size/actual size)

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6
Q

Photosynthesis Equation

A

6CO2 + 6H2O  light  C6H12O6 + 6O2

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7
Q

Respiration Equation

A

C6H12O6 + 6O2  6CO2 + 6H2O + ATP

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8
Q 
Here is the adaptation, how do they benefit the exchange substance?
Large Surface Area
Thin
Selectively Permeable
Diffusion Gradient
A

Large Surface Area Greater surface for diffusion to take place
Thin Short diffusion pathway
Selectively Permeable Control what goes in and out of the cell
Diffusion Gradient Large diffusion gradient - increased rate of diffusion

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9
Q

Label a leaf diagram

A

google it or smthing idk

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10
Q

What is Countercurrent Flow and how is it better than parallel?

A

.The blood is always next to water with higher level of oxygen
.Blood already loaded with O2 meets water which has maximum concentration of oxygen
.Therefore oxygen diffuses into the blood
.Blood with low O2 concentration meets water that has had most of its O2 removed
.Diffusion still happens
.This results in the maintenance of a favourable O2 gradient across the whole gill
.This allows the maximum O2 diffusion (80% of the available O2 in absorbed)
.Only 50% would be possible with parallel flow

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11
Q

Draw and label a paralel flow graph

A

check notes

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12
Q

Label the human respiratory system

A

google it

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13
Q

What are alveoli?

A

.Alveoli are located at the end of bronchioles
.They are the site of gas exchange in mammals
.Tiny air sacs (100-300µm)

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14
Q

Describe the process of inspiration

A
  1. External ICM contract
  2. Internal ICM relax
  3. Ribs pulled up and out
  4. Volume in thorax increases
  5. Diaphragm contracts (flattens)
  6. Further volume increase inside the thorax
  7. Increased volume in thorax leads to reduced pulmonary pressure.
  8. Pulmonary pressure now less than atmospheric pressure
  9. Air is drawn into the lungs from outside (equalises the pressure)
  10. The lungs inflate
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15
Q

Describe the process of expiration

A
  1. Internal ICM contract
  2. External ICM relax
  3. Ribs to move down and inwards
  4. Decreases volume of the thorax
  5. Diaphragm relaxes (arches upwards)
  6. Further decrease in thorax volume
  7. Decreased volume in thorax increases pulmonary pressure
  8. Pulmonary pressure now greater than atmospheric pressure
  9. Air is forced out of the lungs
  10. Lungs deflate.
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16
Q

What is a risk factor for lung disease, with exampels

A

.Increase the probability of suffering from lung disease
.Chronic obstructive pulmonary disease (COPD)
.Includes emphysema and chronic bronchitis
 Smoking
 Air pollution
 Genetic make up
 Infections
 Occupation

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17
Q

Describe and explain emphysema? Like literally just splurge out everything you know about it

A

.Loss of elasticity preventing expansion and contraction
.Common in smokers
.Healthy lungs contain elastic tissue made from elastin (protein)
.Stretches when we inhale, springs back when we exhale
.In emphysematous lungs the elastin has been permanently stretched
.Lungs are no longer able to expel all of the air from the alveoli
.The surface area of the alveoli is reduced
.Some alveoli burst
.Little gas exchange occurs

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18
Q

What is digestion?

A

.Digestion it the process in which large molecules are hydrolysed by enzymes into small molecules which can be absorbed and assimilated

19
Q

Label the digestive system

A

check notes

20
Q

What does the salivary gland sdo?

A

.Produce saliva
.Saliva is supplied via a duct to the mouth
.Contains amylase which hydrolyses starch into maltose

21
Q

WHat does the oesphagus do?

A

.Carries food to the stomach

22
Q

WHat does the stomach do?

A

.Muscular sac
.Inner lining produces enzymes
.Stores and digests food (mainly proteins)
.Has glands that produce enzymes which digest proteins

23
Q

What does the pancreas do?

A 
.Large gland
.Produces pancreatic juice
-	Protease
-	Lipase
-	Amylase
24
Q

WHat does the ileum do?

A

.Long muscular tube
.Walls and glands produce enzymes
.Walls are folded into villi and microvilli
.Absorption into bloodstream

25
Q

What does the large intestein do?

A

.Absorbs water

.Most from secretions produced by digestive glands

26
Q

WHat does the rectum do?

A

.Final section of intestine
.Stores faeces
.Faeces egested by the anus

27
Q

What is physical digestion?

A 
.Teeth and chewing
.Stomach and churning
-	Initial breakdown of large molecules
.Larger surface areas to volume ratio
.Aids enzyme action
28
Q

WHat is chemical digestion?

A

.Hydrolysis of large insoluble molecules into small soluble molecules
.Carried out by enzymes and uses hydrolysis

29
Q

A variety of enzymes are used for digestion. Explain how the digestive system ensures that they are provided with suitable conditions.

A

Saliva maintains the neutral pH by using mineral salts needed for amylase, while the stomach produces HCl to provide a lower pH for proteases. Bile and alkaline salts neutralises the acidic conditions for the pancreases which allows the amylase to function. VV

30
Q

Describe and explain Lipid Digestion

A

.Hydrolysed by lipases produced in the pancreas
.Hydrolyse ester bonds to form fatty acids and monoglycerides
.Lipids are first broken down into micelles by bile salts produced by the liver
.This process is called emulsification

31
Q

Describe and explain bile salts

A

.One end is soluble in fat (lipophilic) but not in water (hydrophobic)
.Other side is insoluble in fat (lipophobic) but soluble in water (hydrophilic)
.Fat is prevented from sticking back together

32
Q

Describe Protein Digestion

A

Peptidases (proteases) hydrolyse peptide bonds in proteins

33
Q

What are the 3 main forms of protein digestion? descirbe them

A

Endopeptidases Hydrolyse the peptide bonds in the central region of a protein forming a series of peptide molecules
Exopeptidases Hydrolyse peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidases
Dipeptidases Hydrolyse the bonds between the two amino acids of a dipeptide. They are membrane bound and part of the cell surface membrane of the epithelial cells lining the ileum

34
Q

Explain how the structure of the ileum is adapted to maximise exchange (5 marks)

A

Folded inner walls (microvilli) to increase surface area. The thin walls are lined with epithelia cells, and there are lots of capillaries for a constant blood supply. In addition, there are muscular walls that can move which helps maintain a concentration gradient (movements mix food).

35
Q

Amino acids and monosaccharides such as glucose are absorbed into the blood using co-transport
Describe the process of co-transport.

A
  1. Na+ actively transported out of epithelial cell by Na+/K+ pump into the blood.
  2. Maintains higher concentration of Na+ in lumen than inside epithelial cells.
  3. Na+ diffuse into epithelial down concentration gradient.
  4. They carry with them amino acids or glucose.
  5. Glucose/amino acids pass into the blood plasma by facilitated diffusion.
36
Q

Describe the Absorption of Triglycerides

A
  1. Lipid mixed with bile salts
  2. This forms micelles
  3. Monoglycerides and fatty acids are released
  4. Monoglycerides and fatty acids are absorbed through the membrane of the ileum
  5. Monoglycerides and fatty acids are converted back to triglycerides in the endoplasmic reticulum
  6. Triglycerides are packaged into chylomicrons
  7. Chylomicrons released by exocytosis
  8. Chylomicrons go into lymphatic vessels and then into the bloodstream
37
Q

What are chylomicrons?

A

.chylo = milky micron = small = small milky globules
.A small fat globule composed of protein (1-2%) and lipid
.They transport fat from the intestine to the liver and to adipose (fat) tissue
.After a fatty meal, the blood is so full of chylomicrons that it looks milky
.The chylomicrons are synthesized in the mucosa (the lining) of the intestine

38
Q

Define triglyceride

A

Lipid consisting of one glycerol and 3 fatty acids

39
Q

Define monoglyceride

A

Lipid consisting of one glycerol and 1 fatty acid

40
Q

Define micelle

A

Lipid molecules arranged in spherical forms due to hydrophilic head and hydrophobic tail

41
Q

Define chylomicrons

A

small particles consisting of lipid and lipoproteins

42
Q

Define exocytosis

A

bulk movement of material out of the cell through the cell surface membrane

43
Q

Define lacteals

A

Lymphatic vessels of the small intestine which absorb digested fats

AQA A Level Biology (19 decks)

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