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Biology additional edexcel > B2.3 Common systems page 90 > Flashcards

B2.3 Common systems page 90 Flashcards

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1
Q

Why are there gaps in fossil records?

A
  • fossils don’t always form
  • soft tissue decays
  • some fossils haven’t been found yet
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2
Q

What is the fossil record?

A

A collection of fossils from different periods of time that can be used to form a hypothesis about the history of life on Earth

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3
Q

What is a pentadactyl limb?

A

A five fingered limb structure

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4
Q

How does the pentadactyl limb provide evidence for evolution?

A

It suggests that all vertebrates evolved from one common ancestor because most vertebrates have a pentadactyl limb

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5
Q

What is growth?

A

An increase in size, length or mass

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6
Q

What are meristems?

A

Places just behind the tips of roots and shoots where plant cells keep dividing

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7
Q

How do plants get bigger?

A
  • cells in the meristem divide

- these then elongate

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8
Q

What is elongation in plant cells?

A

The lengthning of cells after division

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9
Q

What is differentiation in plants?

A

The specialisation of plant cells after elongation

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10
Q

What are stem cells?

A

Cells that can differentiate into a specialised cell

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11
Q

What is the difference between adult and embryonic stem cells?

A

Embryonic stem cells can differentiate into almost any kind of cell whereas adult stem cells have a more limited range

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12
Q

How much blood does the average adult contain?

A

5 litres

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13
Q

What is blood made up of?

A
  • plasma
  • red blood cells
  • white blood cells
  • platelets
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14
Q

What percentage of blood is plasma?

A

55%

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15
Q

What percentage of the blood are white blood cells and platelets?

A

<1%

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16
Q

What percentage of the blood are red blood cells?

A

45%

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17
Q

What colour is plasma?

A

Yellow

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18
Q

What does plasma do?

A

Transport dissolved substances like carbon dioxide, food substances and hormones

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19
Q

What pigment causes red blood cells to be red?

A

Haemoglobin

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20
Q

What do red blood cells do?

A

Transport oxygen to cells in the form of oxyhaemoglobin

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21
Q

What is formed when oxygen combines with haemoglobin?

A

Oxyhaemoglobin

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22
Q

What type of reaction is the combining of oxygen and haemoglobin?

A

A reversible reaction

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23
Q

When does oxygen combine with haemoglobin?

A

When the blood passes through the lungs

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24
Q

What is the shape of a red blood cell?

A

A biconcave disc

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25
Why does a red blood cell's biconcave shape make oxygen absorbption more efficient?
It gives a larger surface area to volume ratio
26
Why does a red blood cell's lack of nucleus increase the amount of oxygen it can carry?
It makes more room to carry as much haemoglobin as possible
27
Do white blood cells or red blood cells have a nucleus?
White blood cells
28
What do white blood cells do?
Defend the body against disease
29
How do white blood cells destroy pathogens and foreign cells?
- they produce antibodies that match the antigens of the pathogen and bind to them - they surround the foreign cells
30
Why don't platelets have a nucleus?
Because they are fragments of cells
31
What do platelets do?
Make the blood clot
32
What is a tissue?
A group of the same types of specialised cells
33
What is an organ?
A group of several different tissues working together to carry out a particular function within the body
34
What is an organ system?
A group of organs working together to carry out a particular function
35
What is deoxygenated blood?
Blood low in oxygen
36
What is oxygenated blood?
Blood high in oxygen
37
What do arteries do?
Transport blood away from the heart
38
What do veins do?
Transport blood to the heart
39
What does the pulmonary vein do?
Bring oxygenated blood from the lungs to the heart
40
What does the pulmonary artery do?
Bring deoxygentated blood from the heart to the lungs
41
What do valves do?
Make sure the blood in the heart goes in the right direction
42
What do tendons in the heart do?
Stop valves from turning inside out
43
What does the superior vena cava do?
Bring blood from the upper body to the right atrium
44
Which side of the heart is bigger?
The left
45
What does the inferior vena cava do?
Bring blood from the lower body to the right atrium
46
What seperates the two different sides of the heart?
The septum
47
What happens when the right atrium is full?
Muscles in the wall contract to force blood through the valves into the right ventricle
48
What happens when the right ventricle is full?
The muscles of the ventricle wall contract to force blood through the valves into the pulmonary artery
49
What happens to deoxygenated blood when it reaches the lungs?
It becomes oxygenated because it picks up oxygen
50
What atrium does the pulmonary vein go to?
The left atrium
51
What happens when the left atrium is full?
It contracts to force blood through the valves into the left ventricle
52
What happens when the left ventricle is full?
It forces the blood through a valve into the aorta
53
What does the aorta do?
Carry blood from the left ventricle to the rest of the body
54
What type of blood is found in the left side of the heart?
Oxygenated blood
55
What type of blood is found in the right side of the heart?
Deoxygenated blood
56
Why is the muscle wall on the left side of the heart thicker than the right side?
It has to pump blood all around the body instead of just around the lungs so it takes more energy
57
What are the three types of blood vessels?
- arteries - veins - capillaries
58
Why do arteries have strong, thick walls?
The blood has to be under high pressure to reach all parts of the body
59
What do capillaries do?
Allow substances to diffuse into and out of the blood from tissues and cells
60
What type of blood vessels have the thinnest walls?
Capillaries
61
Why do veins have a large space for blood to flow?
Because the blood flows slowly and at low pressure
62
What makes up the circulatory system?
The heart and blood vessels
63
What is digestion?
The process of breaking down the large insoluble molecules in food into smaller soluble ones
64
What is a bolus?
A ball of chewed food
65
Why does the mouth chew food to break it up into small pieces?
To increase the surface area for digestive enzymes to work on
66
What does saliva do in the digestive system?
- lubricate the bolus to make it easier to swallow | - start to break down the starch in food because of the amylase found in it
67
What is the digestive system made up of?
- mouth - oesophagus - stomach - small intestine - large intestine - pancreas - anus - liver - gallbladder
68
What process pushes food down the alimentary canal?
Peristalsis
69
What happens to the bolus once it reaches the stomach?
It turns into a thick paste when it's churned up with stomach acid and enzymes by peristalsis
70
What absorbs digested food into the blood in the small intestine?
Villi
71
What organ does most digestion happen in?
The small intestine
72
What does the pancreas do in the digestive system?
Produce enzymes which are released in the first part of the small intestine
73
What happens in the large intestine?
Water diffuses back into the blood
74
Where does digested food go once it is absorbed into the blood?
The liver
75
What does the liver do when it gets digested food molecules?
It breaks them down even more or builds them up into larger molecules
76
What does the liver produce?
Bile
77
What does the gall bladder do?
Store bile to be released when the small intestine needs it
78
What are the three main types of food molecules?
- carbohydrates - proteins - fats
79
What are the simplest forms of carbohydrate called?
Sugars
80
What enzymes break down carbohydrates?
Carbohydrases
81
What does amylase do?
Break down starch into sugars
82
Where is amylase found?
- in the saliva | - in the small intestine
83
What produces amylase?
The pancreas
84
What enzymes digest proteins?
Proteases
85
What are proteins broken down into?
Amino acids
86
Where is pepsin produced?
The stomach
87
What type of enzyme is pepsin?
A protease
88
What pH is stomach acid?
pH 2-3
89
What pH do proteases released in the small intestine work best at?
pH 8
90
What pH do proteases released in the stomach work best at?
pH 2-3
91
What type of enzymes digest fats?
Lipases
92
What do lipases break down fat into?
Fatty acids and glycerol
93
What does bile do to fat?
Emulsify it
94
Why does bile emulsify large globules of fat?
To increase the surface area to volume ratio so that it's digested more quickly
95
Is bile acidic or alkaline?
Alkaline
96
Why is bile alkaline?
It helps neutralise the acid from the stomach so that the protease enzymes work better
97
What happens to large globules of fat when bile emulsifies them?
They are broken down into tiny droplets
98
Why do villi increase the amount of digested food that can diffuse into the blood?
They increase the surface area of the small intestine

Biology additional edexcel (3 decks)

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