B2: Scaling up Flashcards
(128 cards)
1
Q
what is diffusion
A
- diffusion is the net movement of particles from a region of high concentration to a region of low concentration, down a concentration gradient, until they are evenly spread
2
Q
what is concentration
A
amount of particles present in a set amount of volume
3
Q
what’s a concentration gradient
A
difference in concentration between 2 areas
4
Q
what does it mean that diffusion is a passive process
A
it doesn’t require energy
5
Q
where does diffusion occur in the body
A
- in cells
- blood transports substances such as glucose and oxygen around the body
- diffusion is one process in which particles pass through the cell membrane form a region of high concentration to an area of low concentration
6
Q
what factors affect the rate of diffusion
A
- distance (particles need to move)
- concentration gradient
- surface area (of membrane)
- temperature
7
Q
how does distance increase the rate of diffusion
A
- decreasing distance the particles need to travel
- takes less time for particles to travel a shorter distance
> eg blood capillaries are one cell thick, which increases rate of diffusion of gases in/out of blood stream
8
Q
how does concentration gradient increase the rate of diffusion
A
- increasing the concentration gradient
- the steeper the conc gradient, the greater the net movement of particles
> eg plant cells use co2, so the concentration of co2 drops inside plant cell, increasing the diffusion rate of co2 into the cells
9
Q
how does surface area increase the rate of diffusion
A
- increasing the surface area
- more space for diffusion, so more particles can move in a period of time
> eg small intestine wall is highly folded, increasing the surface area that’s in contact with blood stream, which increases rate of diffusion of molecules produced in digestion ie. glucose and amino acids
10
Q
how does temperature increase the rate of diffusion
A
- increasing the temperature
- particles gain more kinetic energy causing them to move faster and collide with cell membrane more often causing rate of diffusion to increase
11
Q
what is osmosis
A
- osmosis is the net movement of water molecules from an area of high water potential to an area of lower water potential across a partially permeable membrane
- water will travel from where there are more water molecules to where there are less (down a concentration gradient)
12
Q
what is water potential
A
- water potential is the concentration of free water molecules
13
Q
what has the highest possible water potential
A
- pure water as all the water molecules are free to move
14
Q
the greater the ___, the greater the rate of osmosis
A
- the greater the difference in water potential
15
Q
what is a hypertonic condition
A
- solution on outside is more concentrated than other solution
- solution outside has lower water potential
- particles move out of cell into concentrated solution
16
Q
what is a hypotonic condition
A
- solution on outside is more dilute than other solution
- solution outside has higher water potential
- particles move into the cell into concentrated
17
Q
what is an isotonic condition
A
- both solutions are of equal concentration
- no net movement of water
18
Q
state what happens in the 3 conditions during osmosis in plant cells
A
- hypertonic : cell placed in more concentrated solution + loses water by osmosis + cell membrane collapses away from cell wall - cell is now plasmolyzed
- hypotonic : cell placed in dilute solution + gains water by osmosis + pressure in cell increases (turgor pressure) - cell is now turgid
- isotonic : cell placed in solution with equal concentration + no net movement of water - cell remain same
19
Q
state what happens in the 3 conditions during osmosis in plant cells
A
- hypertonic : cell placed in more concentrated solution + loses water by osmosis - cell becomes crenated (shrinks and wrinkles)
- hypotonic : cell placed in dilute solution + cell takes up water and swells / might burst - cell lysis
- isotonic : cell placed in solution of equal concentration + no net movement of water - cell remains same
20
Q
what is active transport
A
- active transport is the movement of particles from a region of low concentration to an area or high concentration, against a concentration gradient using energy (ATP) released during respiration
21
Q
give some examples of active transport
A
- movement of minerals from soil into plant roots
- movement of glucose into blood from small intestine
22
Q
what is mitosis
A
- it’s the process by which body cells divide
23
Q
what does mitosis produce
A
- each cell divides to produce 2 genetically identical daughter cells
> they are clones
24
Q
why is mitosis needed
A
- growth
- repair damaged tissue
- replacement of worn out cells
- asexual reproduction
25
what are the stages of the cell cycle
1. DNA replication (S phase)
2. cell growth
3. movement of chromosomes - mitosis
4. cytokinesis
5. growth of daughter cell
26
describe the DNA replication (S phase)
1. DNA molecule unzips forming 2 separate strands
2. bases are exposed
3. free DNA nucleotides pair up with their complementary bases
4. new backbones form producing 2 identical DNA molecules
27
what happens after DNA replication in cell cycle
- cell growth in preparation for cell division
28
how do chromosomes move (in cell cycle)
- chromosomes line up across centre of cell
- the 2 identical copies of each chromosome separate and move to opposite ends of each cell
- the cytoplasm and cell start to divide creating 2 new nuclei
29
what is cytokinesis
- after the movement of the chromosomes, the cell membrane pinches inwards to separate and enclose the 2 new nuclei and pinches off to split the original cell into 2 genetically identical daughter cells
30
what is the importance of cell differentiation
- to allow organisms to become more efficient
31
what does it mean if a cell differentiates
- cells become specialised to perform a particular job
- this means that the structure changes so that it's better adapted to perform its function
32
how are sperm cells specialised to transfer genetic material to the egg
- flagellum (tail) for movement
- lots of mitochondria to provide energy from respiration for movement
- acrosome (contains enzymes) digests through egg membrane to allow transfer of genetic material
- streamlined heads = faster movement
33
how are red blood cells specialised to transport oxygen
- biconcave disc increasing surface area to speed up diffusion of oxygen and co2
- haemoglobin (red pigment) which binds to oxygen forming oxyhaemoglobin
- no nucleus allowing more space for haemoglobin
34
how are palisade cells specialised for carrying out photosynthesis
- found near surface of leaf
- have lots of chloroplasts
- regular shape allowing cells to be closely packed to maximise absorption of sunlight
35
how are ciliated epithelial cells specialised to carry out their function in the respiratory tract
- found in airways
- cilia (tiny hairs) on top of cells
- goblet cells produce sticky mucus
- cilia sweep mucus away from lungs into back of throat and then swallowed
> the bacteria present are killed in stomach thus preventing infection
36
what are stem cells
- stem cells are undifferentiated cells and can develop into lots of different types of cells by mitosis
37
what are the 2 main types of stem cells found in animals
- embryonic stem cell
- adult stem cell
38
where are embryonic stem cells found, what can they develop into and why are they used
- found in embryos
- can develop into all types of cells
- used for growth and development
39
where are adult stem cells found, what can they develop into and why are they used
- found in various body tissues such as ; bone marrow, brain and skin
- can't develop into all types of cells
> they differentiate into a few cells depending on where they are found
- used for replacement of damaged and worn out cells
40
what happens to adult stem cells when an animal if fully grown
- stem cells remain in non-dividing state for years
- only when activated by disease or tissue injury do the cells start to divide again
- this generates many cells which can be used to repair damage
41
where are stem cells found in plants
- only found in the meristems (growing parts of plants)
42
what do stem cells in plants do
they allow the:
- bud to grow into shoots or flowers
- stem to thicken
- root tip to grow longer
43
what is the difference between embryonic and adult stem cells
- embryonic stem cells can differentiate into any type of cell but adult stem cells can only differentiate into cell types from the tissue the stem cells are in
44
what are stem cells used for
stem cells have potential to treat a wide range of medical conditions:
- Parkinson's disease
- type 1 diabetes
- spinal cord injury
they are also used for growth and repair
45
why are exchange surfaces needed for large multicellular organisms
- they have a small surface area: volume ratio so the rate of diffusion wouldn't be fast
- exchange surfaces increase surface area: volume ratio
46
what features make an efficient exchange surface
- large surface area - increases rate of diffusion
- thin walls - shorter distance for diffusion
- good blood supply - maintain steep concentration gradient
- moist lining - gases can only diffuse when dissolved in solution
47
where does gas exchange happen
in the lungs
48
what is the job of the lungs
- to transfer oxygen to the blood and remove waste carbon dioxide from blood
49
what do the lungs have to maximise gas exchange
- millions of little air sacs called alveoli where gas exchange takes place
50
what are alveoli used for
- increases surface area of lungs
- maximises the rate of diffusion of oxygen into bloodstream and CO2 out of
51
how are alveoli adapted to ensure efficient gas exchange
- huge surface area through spherical shape
- very thin walls (one cell thick) - shorter distance for diffusion of gases
- moist lining for dissolving gases
- good blood supply - steep concentration gradient
52
describe the blood flow process and explain the gas exchange occurring in the alveoli
- blood passing next to alveoli has returned to the lungs from rest of the body via the heart
> so lots of CO2 and very little oxygen in blood - deoxygenated blood
- CO2 diffuses out of blood (high conc) into alveolus (low conc) to be breathes out
- oxygen diffuses out of alveolus (high conc) into blood (low conc)
> oxygenated blood now goes back to heart and around body
53
what are the villi used for
- increases surface area of small intestines
- allows absorption of dissolved food molecules into blood more quicker
54
how are villi adapted to ensure efficient absorption of digested food molecules
- large surface area for diffusion
- Epithelial - thin walls (one cell thick) - shorter distance across which diffusion takes place
- Capillary Network - absorbs sugars + amino acids
- Lacteal - absorbs fatty acids
- Microvilli on Epithelial - further increase surface area
55
what do root hairs do
- take in water and mineral ions
56
what is the circulatory system made up of
- heart
- blood
- blood vessels
57
why is the circulatory system known as a closed system
- because blood remains within these structures
58
what substances does the circulatory system carry to and from the cells
to cells :
- oxygen
- glucose
away from cells:
- carbon dioxide
- urea
59
why is the circulatory system called a double circulatory system
- because blood flows through the heart twice during each circuit of the body
60
why do mammals need a double circulatory system
- double circulatory systems have blood flowing at a higher pressure, allowing it to flow faster and move substances quickly around the body
61
describe the double circulatory system in mammals
- the heart pumps deoxygenated blood to the lungs to take in oxygen
- the oxygenated blood returns to the heart
- the heart pumps the oxygenated blood around the body where it releases oxygen
- the deoxygenated blood returns to the heart
- the cycle continues again
62
what are the 3 main types of blood vessels
- arteries
- veins
- capillaries
63
what are blood vessels
- tube like structures which transport blood around the body
64
what is a lumen
- the hole down the middle of a blood vessel
65
what role does an artery have in the double circulatory system
- arteries carries blood away from the heart under high pressure
66
what role does a vein have in the double circulatory system
- veins carry blood into the heart in low pressure
- they have valves to stop the backflow of blood in the wrong direction
67
what role does a capillary have in the double circulatory system
- capillaries link arteries and veins in tissues and organs
68
describe the structure of arteries and explain it's relevance
- have thick + muscular walls to withstand the high pressure of blood flow
- contain elastic fibres to allow artery to stretch and recoil to push blood forward
- small lumen
- no valves
69
describe the structure of capillaries and explain its relevance
- have very thin walls (one cell thick) - increases rate of diffusion of substances + also low blood pressure
- very small lumen
- no valves
70
describe the structure of veins and explain its relevance
- thin layer of muscle + elastic fibres because blood pressure is low
- large lumen helps blood flow
- valves to prevent backflow of blood
71
at what pressure does blood flow in arteries and why
- blood flows at high pressure due to the strong contractions of the heart
72
at what pressure does blood flow in capillaries and why
- low blood pressure + speed to allow exchange of substances
73
at what pressure does blood flow in veins and why
- low pressure
74
what do arteries branch into
arterioles
75
what do arterioles branch into
capillaries
76
what do capillaries branch into
venules
77
what do venules join up to form
veins
78
what muscle is the heart made from
cardiac muscle
79
cardiac muscles can ____ without receiving a ____ from the ____, and unlike other ____ they never get ____
- cardiac muscles can contract without receiving a nerve impulse from the brain, unlike other muscles they never get tired
80
how many chambers are there in the heart
4
81
what are the 2 smaller chambers at the top called
atria (sing. atrium)
82
what are the 2 larger chambers at the bottom called
ventricles
83
what are between the 2 top and bottom chambers
valves
84
describe the blood flow through the right side of the heart
- deoxygenated blood enters the right atrium through the vena cava
- the atrium contracts, forcing blood through the atrio-ventricular valve and into the right ventricle
- the ventricle contracts, pumping the blood out through the semi-lunar valves to the lungs via the pulmonary artery
85
describe the blood flow through the left side of the heart
- oxygenated blood enters into the left atrium via the pulmonary vein
- the atrium pumps the blood through the atrio-ventricular valves and into the left ventricle
- the ventricle contracts and the blood is pumped out through the semi-lunar valve and out to the whole body via the aorta
86
what is the name of the valve between the atrium and ventricle coming into the heart
- atrio-ventricular valve
or
- tricuspid / bicuspid valve
87
what is the name of the valve between the ventricle and the arteries leading out of the heart
- semi-lunar valves
88
name the arteries which carry blood away from the heart, where to, and which side they are on
- right side - pulmonary artery - to lungs
- left side - aorta - to body
89
name the veins which carry blood into the heart, where from, and which side they are on
- right side - vena cava - from the body
- left side - pulmonary vein - from the lungs
90
which ventricle has the thickest wall and why
- left ventricle has thicker wall because it needs to pump the blood all around the body and so needs to be under a greater pressure
91
why are the walls of the atria thinner than the ventricles
- because blood is pumped out of the heart at a greater pressure from the ventricles and it enters at a lower pressure
92
what do the coronary arteries do
- they supply blood to the heart by 2 coronary arteries, which branch from the base of the aorta (biggest artery in body)
93
what is blood made up of
- red blood cells
- white blood cells
- plasma
- platelets
94
what are red blood cells and their transport functions in the blood
- small biconcave cells with no nucleus
- made in bone marrow
- have protein called haemoglobin - transports oxygen from lungs to all around the body
- fit through lumen of capillary one cell at a time
95
what is plasma and its transport function in the blood
- over half of blood is plasma
- plasma is a pale yellow liquid part of the blood
- over 90% water and has many substances dissolved in it
> digested food (glucose, amino acids, mineral salts)
> waste substances - CO2 taken to lungs, urea taken to kidneys
> hormones + antibodies
96
what are white blood cells
- large cells containing nucleus which helps prevent diseases
- they make antibodies to destroy pathogens
97
what are platelets
- small parts of cell membranes which helps blood to clot
> this blocks wound and prevents entry of pathogens and loss of blood
98
why do plants need a transport system
- the volume: surface area ratio is too big so diffusion wont be fast and transport systems will be needed
99
what are the 2 transport systems within a plant
- xylem
- phloem
100
what does the xylem transport
- xylems carries water + mineral ions from the roots to the parts of the plants above ground
> e.g. stem, leaves and flowers
- water diffuses into roots by osmosis
- mineral ions are taken in my active transport
101
what does the phloem transport
- phloem carries substances made by photosynthesis from the leaves to other areas
102
what is translocation
- movement of sugar produced during photosynthesis, to other areas of the plant
103
what is a vascular bundle
- xylem and phloem that are arrange close together to form a vascular bundle
104
describe the structure of the xylem
- made of dead cells
- thick impermeable cell wall made of cellulose + lignin
- no end walls between cells
- one way flow
105
describe the structure of the phloem
- made of living cells
- thin permeable cell wall
- end walls with perforation - sieve plates - allowing substances to pass through
- two way flow
106
how and where do the vascular bundles provide support
- in the leaf - they form a network of vessels to support soft tissue
- in the stem - they're located around the outer edge to provide support + resist bending
- in the root - they are centrally located allowing the root to anchor the plant
107
what is transpiration
- transpiration is the loss of water from a plant's leaves
108
what is a transpiration stream
- the transpiration stream is the constant flow of water taken up from the roots through the xylem and out of the leaves
109
describe the transpiration stream in simple words
- water absorbed by roots through osmosis
- water travels through the plant up the xylem
- water evaporates from leaf surface
110
what are the adaptations of root hair cells
- elongated cell - increases surface area for water + mineral ion absorption
- thin cell walls - reduce distance for water + mineral ions to pass through
- many mitochondria - for active transport of mineral ions
- large vacuole - to store solutes
111
describe the movement of water in the transpiration steam
- water is lost through stomata (transpiration)
- root hair cells absorb water + mineral ions
- pressure at top of xylem is lower as water evaporates out of leaf
- water moving into xylem from roots increases pressure at bottom
- the difference in pressure forces the water up through the plant
112
what is cohesion
- the attraction of water molecules to each other
113
what is adhesion
- the attraction of water molecules to the inside of the xylem
114
what does the stomata do
- stomata on surface of leaf allow CO2 to diffuse in for photosynthesis
- when open the stomata lets the water evaporate from inside the leaf to outside
115
what do guard cells do
- they allow the stomata to open and close
116
how is water lost from the stomata
- when stomata are open, the water evaporates from leaf to outside (transpiration)
- there's a concentration gradient between water inside and outside leaf
- the water inside leaf ( high concentration) diffuses out into the air ( low concentration)
117
how is uncontrolled water loss prevented
- leaves have waxy cuticle on upper epidermis helping it become waterproof
- most stomata are found on underside of the leaf (where its darker and cooler) - helping slow down the rate of diffusion
- plants in hot climates have fewer and smaller stomata on underside of leaf
118
why and when do stomata close
- at night, hot or dry conditions
- water moves out of cells via osmosis, causing guard cells to become flaccid and close the stomata
> guard cells have shrunken
119
why and when do stomata open
- daytime
- water moves into cells via osmosis, causing
guard cells to become turgid and open the stomata
> guard cells are swollen
120
what type of walls do the stomata have
- thin outer walls
- thick inner walls
121
what are some benefits of the transpiration stream
- constant stream of water keeps the plant cool
- provides plant with constant supply of water for photosynthesis
- water helps support the plant + stops it from wilting by creating turgor pressure
122
what factors affect the rate of transpiration
- light
- temperature
- wind / air movement
123
explain how the rate of transpiration is affected by light
- increased light causes stomata to open wider so rate of transpiration increases as more water evaporates
124
explain how the rate of transpiration is affected by temperature
- increasing temperature causes water molecules to have more kinetic energy so it diffuses out of spongy mesophyll faster
- there's a greater concentration gradient so transpiration increases
125
explain how the rate of transpiration is affected by wind / air movement
- increased air movement causes water molecules on leaf surface to blow away
- the concentration gradient is increased between the leaf and air so water diffuses out more quickly which increases the rate of transpiration
126
what is a potometer
- a piece of apparatus that allows us to measure the rate of water uptake (transpiration) by a shoot
> we can use it to measure transpiration in different conditions
127
describe how a simple potometer can be used to investigate factors affecting rate of transpiration
- cut a shoot (slanted) under water and place in potometer
- take an air bubble into the capillary tube
- as water moves into the shoot and evaporates from the leaves, the air bubble moves towards the plant
- measure how fast the bubble travels which will give you an idea of how fast the plant is transpiring
- rate of movement = distance / time
- refill the capillary tube and repeat measurement - you can change the environmental conditions to investigate
128
how do you calculate the rate of transpiration
- rate of movement = rate of transpiration
rate of movement = distance (mm) / time (s)
