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GCSE Biology OCR A > B2 > Flashcards

B2 Flashcards

1
Q

What is diffusion?

A

🔶The net movement of particles from an area of high concentration to low concentration
🔶passive
🔶small molecules only

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2
Q

Why is diffusion only sufficient for single celled organisms?

A

They have a large SA:V ratio (as they are smaller ) and have low metabolic demands

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3
Q

What are some examples of adaptations for diffusion in the body?

A

Alveoli/ Villi
large SA:V for diffusion of gases
Thin walls to shorten diffusion distance
Good blood supply to create a high concentration

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4
Q

Why is diffusion important for organisms?

A

In order for respiration to occur at a fast enough rate for the body to provide energy to all the organisms, through semi permeable membranes

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5
Q

What factors affect the rate of diffusion?

A

🔴Temperature- particles move faster
🔴concentration gradient- the more steeper , the faster
🔴SA, the larger the more particles can come

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6
Q

What is osmosis?

A

🌀The movement of WATER particles across a semi permeable membrane from an area of high water potential to low water potential
🌀passive process

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7
Q

What is water potential?

A

🌀The measure of FREE water particles.
🌀If there is a solute/ water concentration- the water molecules around it become ‘busy’ and therefore overall it has a low water potential

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8
Q

When is a solution isotonic to the cell?

A

When the solution and the cell have the same water potential and concentration of sugar

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9
Q

When is a solution hypotonic to the cell?

A

The outside solution has a
▫️lower concentration of sugar
▫️higher water potential
▫️osmosis solution to cell

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10
Q

When is a solution said to be hypertonic to a cell?

A

When the solution has
▫️a larger concentration of sugar
▫️lower water potential
▫️osmosis from cell outwards

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11
Q

What happens to a plant cell when placed in a hypotonic solution?

A

Water moves from outside to inside
Making it fat or turgid

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12
Q

What happens when a plant cell is placed in a hypertonic solution?

A

Water moves from cell to outside
Making it flaccid until it collapses and becomes plasmolysed

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13
Q

What happens when an animal cell is placed in a hypotonic solution

A

Hypo- low solute concentration, high w.p
Water moves from solution into cell making it swell until it burst - lysis

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14
Q

What happens when an animal cell is placed into a hypertonic solution?

A

Hyper- high solute concentration, low W.p
Water moves from cell into solution
Cell becomes cremated

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15
Q

What is active transport ?

A

⚪️Movement of particles from an area of low concentration to high concentration
⚪️requires energy
⚪️carrier proteins across the membrane

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16
Q

What are some examples of active transport ?

A

Root hair cells:
🟤Water/ mineral ions form the soil
In your gut:
🟤food from gut into the bloodstream

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17
Q

What is mitosis?

A

Cell division where one cell divides to form two identical daughter cells

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18
Q

Why does mitosis take place?

A

🔴To replace worn out cells
🔴repair damaged tissue
🔴allow growth

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19
Q

Describe interphase

A

🟢cell grows out other organelles eg: mitochondria/ribosome
🟢 46 chromosomes are replicated forming x shape

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20
Q

Describe mitosis

A

🧬The X chromosomes line up at the middle of the cell
🧬Spindle fibres pull them apart to opposite sides of the cell

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21
Q

Describe cytokinesis

A

Two identical daughter cells are made when cytoplasm and membranes divide

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22
Q

How is DNA replicated

A
  1. DNA unzips
    2.free nucleotides bond with the exposed strands
  2. Complementary base bonding forming DNA pairs
  3. Whole dna bonds forming new anti parallel strands
  4. Half of original and half of new
  5. Forms an X shape
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23
Q

What is cell differentiation?

A

A cell gaining new sub cellular structures in order for it to be suited to it’s role

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24
Q

How is a red blood cell a specialised cell?

A

🔴no nucleus, to make room for haemoglobin
🔴biconcave shape to increase SA:V , increasing diffusion
🔴full of haemoglobin to carry as much as possible
🔴flexible to fit through very narrow blood vessels

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25
How as a sperm cell a differentiated cell ?
🔵flagellum to move the sperm to the ovum 🔵lots of mitochondria, for respiration, for energy to move 🔵acrosome to transfer genetic material to ovum
26
How is a fat cell a differentiated cell?
Can expand 1000x more than the original size to store fat
27
How are root hair cells differentiated cells?
🟤large SA:V ratio so that water can be diffused 🟤mitochondria for active transport as a lot of energy is required 🟤large vacuole helps the concentration gradient for osmosis
28
How are the xylem cells differentiated cells?
🟢lignin , hollow tube ,so that water can move through 🟢lignin also helps against the pressure of the water
29
How are palisade cells differentiated cells?
🟢full of chloroplast maximising the absorption of sunlight 🟢regular shape to allow a lot to be filled closely
30
What are stem cells?
Undifferentiated cells which can undergo division to produce many similar cells
31
Describe embryonic stem cells
👶Can differentiate into all cell types 👶Found from an embryo, when a sperm cell and egg fuse
32
Describe adult stem cells:
👱🏼‍♂️found in body tissues- bone marrow/brain 👱🏼‍♂️cannot form some but not all types of cells 👱🏼‍♂️used to repair damage
33
Describe meristem stem cell
🌿found in roots and shoot tips 🌿can differentiate into any type of plant and have this ability throughout life 🌿can be used to make clones of plants cheaply
34
What are differences between plant and animal differentiating cells?
In Animals differentiating only happens at young age whereas in the plant it happens life long
35
How do you calculate the SA:V ratio ?
Keep it in ratio SA: V -simplified
36
How do you calculate the rate of something?
1/time
37
Why do multicellular organisms require adapted exchange surfaces?
They are too big , have a small SA:V ratio and therefore diffusion does occur fast enough to meet the cell’s demands
38
Why are transport systems required?
Once the substances have been diffused through your body, it needs to be transported to where needed Eg: circulatory system
39
What is the function of the circulatory system ?
To transport substances around the body to cells that need them Eg: oxygen for respiration
40
Why do mammals require a double circulatory system?
The blood is pumped twice, increasing the pressure and the speed at which the materials are transported Metabolic rate is higher and need a faster system
41
Describe the structure of the double circulatory system:
1. Deoxygenated blood flows into right atrium 2. then to right ventricle pumping it to lungs 3. The oxygenated blood flows into the left atrium 4. Then to left ventricle- pumps oxygenated blood around the body
42
Describe the muscular wall of the heart
❤️Provide a strong heartbeat ❤️Left ventricle is thicker as blood needs to be pumped all around the body
43
What do the valves do?
Make sure the blood does not flow backwards
44
What do the pulmonary arteries do?
Carry deoxygenated blood from the right ventricle to the lungs
45
what do the pulmonary veins do?
Carry oxygenated blood from the lungs to the left atrium
46
What does the aorta do?
Carry oxygenated blood from the left ventricle to the body
47
What does the veins cava do?
Carry deoxygenated blood from the body to the right atrium
48
What are atriums?
The top two chambers of the heart
49
What are ventricles?
The bottom two chambers of the heart
50
How does the heart work
🫀Blood flows into the right atrium through the vena cava and left atrium through the pulmonary vein 🫀the atria contract pushing the blood into the ventricles to the pulmonary artery and aorta 🫀 valves close to make sure there is no back flow
51
What do veins do?
Carry blood towards the heart
52
What do arteries do?
Carry blood away from the heart
53
What do capillaries do?
Allows blood to flow very close to cells to enable substances to move between them
54
Describe arteries :
❤️‍🔥Layers of muscle to make them strong ❤️‍🔥Elastic fibres allow them to stretch ❤️‍🔥Carry high pressure, small lumen
55
Describe veins:
💙wide lumen to carry low pressure 💙thin walls 💙valves to prevent back flow
56
Describe capillaries:
🐛one cell thick to create a small distance for diffusion 🐛permeable walls so that substances can move across 🐛very small lumen, large Sa: V ratio for diffusion
57
Describe plasma:
🤍A liquid which carries all the components of the blood 🤍mainly made up of water 🤍materials are transported by being dissolved in plasma
58
What do platelets do?
Clot the blood
59
What do white blood cells do?
⚪️Fight diseases by making antibodies ⚪️Change shape to engulf microorganisms
60
What is the function of xylem?
To transport water from the roots into leaves of the plants due to loss in transpiration
61
What is the function of phloem?
Transports dissolves sugars produced in photosynthesis from the leaf to other areas of the plant
62
Describe the structure of xylem tissue:
🪵made up of dead cells 🪵no end walls 🪵carried water/minerals 🪵is one way only 🪵thick walls made from cellulose cans strengthened with lignin
63
Describe the structure of phloem tissue
🎋transports food and water 🎋both ways 🎋has sieve plates 🎋living cell 🎋permeable
64
What is transpiration?
The of evaporation water from the stomata .
65
What is the transpiration stream?
The constant flow of water from the roots , through the xylem and out of the leaves.
66
Describe the transpiration steam process:
1.Water lost from the leaves of the plants by evaporation from the stomata 2. Water is drawn up from the roots xylem by osmotic pull to replace water lost 3. Water comes from soil due to osmosis, root hair cells
67
How does stomata control the loss of water?
The kidney shaped guard cells 🍃when water is available they swell up and open the stomata * open in light, close in dark 🍃found at the bottom of the leaf to minimise the rate of evaporation as it is cooler
68
What factors affect transpiration?
🌱Light intensity - more photosynthesis, stomata open more, more evaporation, more transpiration 🌱temperature-⬆️ 🌱increased air movement -steeper concentration gradient, more evaporation, more transpiration 🌱 humidity- ⬆️decreases transpiration
69
How do you use a potometer?
Set underwater to remove air bubbles in the xylem See bubble move up the meter
70
what is translocation?
The phloem moving food up and down from the leaves to cells for immediate or storage use
71
What sort of substances can diffuse?
Only small particles such as : glucose, water, urea,oxygen &amino acids
72
Why does the body need adaptations like villi and alveoli?
They allow molecules to be transported in and out of cells , by increasing the rate of diffusion, and a fast enough rate for the body
73
Why does cell differentiate?
Producing specialised cells , allow the organism to be more efficient
74
Why is mitosis required?
🔴growth for the organism 🔴replacing damaged cells 🔴repair muscle tissues
75
How is plasma adapted to carry blood?
🟣clear and watery, suitable medium to transport water soluble molecules
76
What substances get transported around the body
🟠oxygen 🟠carbon dioxide 🟠water 🟠urea 🟠dissolved food molecules
77
What are semi lunar valves?
Attached at the point the pulmonary artery and aorta leave the ventricles
78
Where are the tricuspid valves?
On the right hand side of the heart, between the atrium and ventricles
79
What are the bicuspid valves?
The left side of the heart , between atrium and ventricle
80
What are xylem’s adaptations to it’s function ?
🪵 walls are strengthened with lignin , to help it withstand pressure from water movement
81
What are some adaptations for phloem to it’s function?
The movement of substances are two way, so that it can be delivered to all areas of the plant
82
What does the potometer measure?
The volume of water taken up by the shoot
83
How can a potometer be used to investigate factors that affect the rate of water uptake ?
1. Air bubble introduced in capillary tubing 2. As water moves into the shoot and evaporates from it’s leaves , the air bubble moves towards the plant 3. Start timer 4. Measure distance, and rate of transpiration 5. Refill the capillary tube in different environment conditions
84
How do you calculate the rate of transpiration?
Distance travelled by air bubble ➗time taken

GCSE Biology OCR A (7 decks)

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