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IGCSE Biology Edexcel > Structure and Functions in Living Organisms > Flashcards

Structure and Functions in Living Organisms Flashcards

1
Q

Level of organisation

Cells, Tissues, Organs, Organ System

A
  • A cell is a group of organelles working together to perform the same function
  • A tissue is a group of cells working together to perform the same function
  • An organ is a group of tissues working together to perform the same function
  • An organ system is a group of organs working together to perform the same function
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2
Q

What elements are found in carbohydrates (glucose)+ how to test for it

A
  • Carbon, Hydrogen and Oxygen
  • Heat solution in water and add Benedict’s solution, turns from blue to:
  • green or yellow in low concentration
  • brick red in high concentration
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3
Q

What elements are found in protein + how to test for it

A
  • Carbon, Hydrogen, Oxygen and Nitrogen
  • Add biuret solution, turns from blue to purple
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4
Q

What elements are found in lipids + how to test for it

A
  • Carbon, Hydrogen and Oxygen
  • Add ethanol + water to the solution and shake, if positive test a milky white emulsion forms
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5
Q

What is starch made up of and how to test for it

A
  • Made up of simple sugars (glucose) joint together
  • Add iodine solution, if positive test the sample should turn blue-black
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6
Q

What are enzymes

A
  • Biological catalysts
  • Which speed up the rate of reaction without being used up
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7
Q

What is metabolism

A

It’s the rate at which chemical reactions take place in the body

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8
Q

What’s an active site

A

An area of an enzyme where substrate attaches

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9
Q

What is diffusion

A
  • net movement of particles
  • from area of high concentration to an area of low concentration
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10
Q

The effect of too high temperature on enzyme activity + the effects of too high or too low pH on enzyme activity

A
  • Decreases activity
  • Enzyme denatures and substrate can no longer fit the active site
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11
Q

What are the factors affecting diffusion

A
  • Temperature
  • Concentration gradient
  • Surface area to volume ratio
  • Distance
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12
Q

What is osmosis

A
  • net movement of water molecules
  • across a partially permeable membrane
  • from area of high water conc. to area of lower water conc.
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13
Q

What is active transport

A
  • net movement of particles
  • from area of low concentration to an area of high concentration
  • requiring energy
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14
Q

What’s a limiting factor

A
  • Factor in a reaction which is in the shortest supply
  • Lack of this factor is the reason why the rate of reaction no longer increases
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15
Q

What is the process of photosynthesis

A
  • Photosynthesis is the process where plants make their own ‘food’ (the food it produces is glucose)
  • Chloroplast contains chlorophyll which absorbs sunlight and uses the energy to convert CO2 and H2O into glucose and water
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16
Q

Why is rate of photosynthesis low in the morning

A
  • Carbon dioxide levels are high
  • Temperature is a limiting factor
  • Low temperature inhibits enzyme activity
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17
Q

Why is rate of photosynthesis high at midday

A
  • High temp maximises enzyme activity
  • Carbon dioxide is a limiting factor as it is in the shortest supply
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18
Q

Whats magnesium needed for in plants

A
  • Needed to produce chlorophyll in plants
  • Not enough leads to leaves yellowing
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19
Q

Whats nitrogen needed for in plants

A
  • Nitrates = source of nitrogen which is needed to make amino acids for protein
  • Not enough causes stunted growth and yellowing of leaves
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20
Q

What’s contained in the top half of a leaf + their functions

A
  • Waxy Cuticle: Prevent evapouration of water
  • Upper epidermis: Transparent to allow light to enter leaf
  • Palisade Mesophyll: Contains lots of chloroplast for photosynthesis
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21
Q

What’s contained in the bottom half of a leaf + their functions

A
  • Spongy mesophyll air spaces: Allows gases to diffuse
  • Xylem: Allows entry of water into leaf by tranpiration stream
  • Phloem: Takes away glucose produced from photosynthesis
  • Guard cells: Controls opening and closing of stomata
  • Stomata: Allows CO2 to enter the leaf
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22
Q

How is a leafs structure better adapted for photosynthesis

A
  • Thin; so gases don’t have to diffuse far
  • Large surface area; so it can absorb more light
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23
Q

Carbohydrates
source + function

A
  • Pasta, rice
  • Provides energy
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24
Q

Proteins
source + function

A
  • Meat
  • Important for growth and repair of muscles
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25
Q

Lipids / Fats
source + function

A
  • Butter
  • Provides energy + provides insulation
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26
Q

Vitamins A, C and D
source + function

A

A:
* Liver
* Helps improve vision

C:
* Oranges
* Helps to prevent scurvy

D:
* Eggs
* Needed for strong bones

LOE

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27
Q

Mineral Ions

Calcium + Iron
source + function

A

Calcium:
* Milk
* Needed to make strong teeth + bones

Iron:
* Red meats
* Needed to make haemoglobin for healthy blood

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28
Q

Fibre
source + function

A
  • Fruits + Vegetables
  • Aids movement of food through gut
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29
Q

Water
function

A
  • Constant supply to replaces water loss from sweating, urinating, breathing
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30
Q

Bile function

A
  • PRODUCED in liver, STORED in gall bladder and RELEASED into the small intestine
  • Bile is alkali, it NEUTRALISES the hydrochloric acid from the stomach
  • BIle EMULSIFIES fat - it breaks down large lipid molecules into smaller ones to increase surface area
31
Q

What is peristalsis

A
  • Muscular contractions that squeeze boluses of food through your gut
32
Q

The Alimentary Canal

What happens in the mouth?

A
  • Teeth break down food into smaller parts
  • Enzyme amylase in the saliva start to break down starch
33
Q

The Alimentary Canal

What happens in the stomach?

A
  • Stomach contracts to break down food into smaller pieces
  • Proteases start to break down proteins in the stomach
  • Produces hydrochloric acid to kill bacteria
34
Q

The Alimentary Canal

What happens in the pancreas?

A
  • Pancreas secretes digestive enzymes into small intestine;
  • Proteases (protein), Amylase (carbs) and Lipase (lipids)
35
Q

The Alimentary Canal

What happens in the small intestine?

A
  • Absorbs nutrients into the body
  • First part is the deodenum and last part is called the ileum
  • The walls of the SI are covered in villi which have a large surface area for more absorption
36
Q

The Alimentary Canal

What happens in the large intestine?

A
  • This is where excess water is absorbed
  • After water’s absorbed, the undigested food leaves the body as faeces
37
Q

How is the structure of villi important

A
  • Villi is covered in microvilli which** increases the SA for absorption** even more
  • Each villus contains capillaries to maintain quick absorption of nutrients
  • In the middle of the villus is a lacteal which is responsible for absorbing fat
38
Q

What is respiration?

A
  • It’s the process of transferring energy from glucose
  • This transferred energy is made into ATP which provides energy to cells
39
Q

Aerobic respiration word + chemical equation

A

Oxygen+Glucose->Carbon Dioxide+Water+ATP
6O2 + C6H12O6 —> 6CO2 + 6H20 + ATP

40
Q

Anaerobic respiration word equation in humans + plants

A

Glucose —–> Lactic acid + energy
Glucose —–> Ethanol + Carbon Dioxide + energy

41
Q

What do the goblet cells and cilia do?

A
  • Goblet cells secrete mucus which traps bacteris
  • Cilia, located in the trachea and lungs, have hair like projections that waft the mucus up to your mouth
42
Q

What happens when you breathe in?

A
  • Intercostal muscles + diaphragm contract/flattens out
  • Thorax increases in volume + ribs move up and out
  • This decreases the pressure drawing air in
43
Q

What happens when you breathe out?

A
  • Intercostal muscles + diaphragm relax
  • Thorax decreases in volume + ribs move down and in
  • This increases the pressure, forcing air out
44
Q

How are alveoli adapted for gas exchange?

A
  • They have large surface area
  • Thin walls to short diffusion pathway
  • Moist to dissolve gases
  • Great blood supply
45
Q

How does smoking effect the body?

A
  • Contains carcinogens leads to lung cancer
  • Smoking damages the walls of alveoli —> decreasing surface area for gas exchange —> disease called emphysema
  • Tar causes cilia to paralyse —> build up of mucus and pathogens —> bronchitis and smokers cough
  • Carbon monoxide binds irreversably to haemoglobin —> reducing amount of oxygen —> heart rate increases to make up, high blood pressure —> increased risk of coronary heart disease and heart attacks
46
Q

Components of blood

A
  • Red blood cells
  • White blood cells
  • Plasma
  • Platelets
47
Q

What do platelets do + how do they do it?

A
  • Clot the blood at the site of a wound
  • In a clot, platelets are held together by a mesh of protein called fibrin
48
Q

What substances are transported in plasma?

A
  • (soluble products) Glucose, Amino Acids
  • Hormones, Carbon Dioxide, Urea

GACHU

48
Q

How are red blood cells adapted for their function?

A
  • Have a bioconcave disc shape, increases surface area to absorb and release oxygen
  • Don’t have a nucleus, frees up space for more haemoglobin so they can carry more oxygen
  • They contain haemoglobin (which contains lots of iron), haemoglobin reacts with oxygen to form oxyhaemoglobin
49
Q

What are the 2 types of white blood cells + explain what their role is

A
  • Phagocytes
  • Lymphocytes
50
Q

How do phagocyte

A

Detect things that are foreign in the body and then engulf the pathogen and digest them

51
Q

How do lymphocytes work + explain memory cells

A
  • Recognise antigens (every pathogen has a unique molecule called antigen)
  • Produce antibodies (proteins) which destroys pathogens by:
  • Labeling the pathogen so it’s easily recognisable by phagocytes
52
Q

How do vaccinations work

A
  • Vaccinations involve injecting dead pathogens into the body which carry antigens
  • They trigger an immune response; your lymphocytes produce antibodies
  • Memory cells will be produced, if those same pathogens infect you, antibodies to kill them will be produced much quicker and in a larger quantity
53
Q

Pulmonary is for…
Hepatic is for…
Renal is for…
Veins
Artieries

A
  • Lungs
  • Liver
  • Renal
  • Bring blood to the heart
  • Take blood away from the heart
54
Q

How is oxygenated blood sent to the body

A
  • Oxygenated blood is brought from the lungs to the pulmonary vein
  • To the left atrium, contracts and forces blood into left ventricle
  • Left ventricle contracts, pumping the blood around the body via the aorta
55
Q

How is deoxygenated blood brought from the body

A
  • Deoxygenated blood is brought from the body to the heart by the vena cava
  • Takes blood into the right atrium, contracts and forces blood into the right ventricle
  • Right ventricle contracts and pumps blood to the lungs via the pulmonary artery
55
Q

How does the heart rate change during exercise?

A
  • When you exercise, you produce more CO2 bc muscles are respiring more
  • High levels of CO2 in blood is detected by the receptors in the aorta and carotid artery (artery in the neck)
  • This sends impulses to the brain, brain sends signla to heart causing it to contract more frequently
56
Q

How does the heart rate change under the influence of adrenaline?

A

*

57
Q

What are some factors that can lead to coronary heart disease

A
  • Having a diet high in saturated fat
  • Smoking
  • Being inactive
  • High blood pressure
57
Q

How are the arteries adapted for its function

A
  • It has a narrow lumen, blood will be forced through at high pressures
  • Thich muscle walls; walls of the artery should be thick to withstand high pressure
  • Elastic fibre walls; to allow arteries to expand
58
Q

How are veins adapted for its function

A
  • It has a wider lumen, blood flows at much lower pressure
  • Therefore the walls don’t need to be as thick
  • They have valves which prevents the backflow of blood
59
Q

How are capillaries adapted for its function

A
  • Capillaries are one cell thick to enable a very short diffusion distance
60
Q

What is excretion

A

Removal of waste products of metabolism

61
Q

What are the excretory products of the body

A
  • Urea in the kidneys
  • Carbon Dioxide from the lungs
  • Sweat from the skin
62
Q

What are auxins

A

Auxins are plant hormones

63
Q

Why do plant grow towards the light

A
  • When a shoot is exposed to light, the auxin accumulates on the side that’s more shaded
  • Makes the cells elongate and shoot bends towards light
63
Q

What’s the difference between hormonal and nervous communication

A
  • Hormonal: Chemicals that travel in your blood
  • Slower messages
  • Responses are long lived
  • They act in a more general area
  • Nervous: Invloves the use of electrical impulses
  • Much faster message
  • The electrical impulses will act on a specific area
  • Responses are short lived
64
Q

How does the CNS coordinate information

A
  • The stimulus (a book) is detected by the receptors
  • They send electrical impulses along the sensory neuron to the CNS
  • Electrical impulses then pass along to the motor neuron to the effector
64
Q

What does the CNS consist of

A

Brain and Spinal Cord

65
Q

What is a synapse

A
  • The connection between 2 neurons, this is where a neurotransmitter is released
  • The nerve signals are transferred by chemicals called neurotransmitter which diffuses across the gap
66
Q

How does a reflec arc work

A
  • The receptor detects the stimulus (fire)
  • Electrical impulses are then sent along the sensory neurons to the CNS
  • In the CNS the sensory neurons pass the electrical impulses to the relat neuron
  • The relay neuron relays the impulses to the motor neuron, which travel along the moto neuron the effector
  • Muscle then contracts and moves hand away from fire
67
Q

What happens to the eye when focusing on distant objects

A
  • Ciliary muscles relax
68
Q
A
69
Q
A

IGCSE Biology Edexcel (5 decks)

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