Transcript Biology Unit 3 revision

Keywords: Active Transport, Osmosis, Diffusion, lungs, alveoli, villi, stomata, root hair cell
Human Kidney
Vital for homeostasis
Everything filtered from blood and then reabsorption
of all the glucose, as well as the mineral ions and water
needed.
Active transport ensures ALL glucose is reabsorbed
and diffusion makes sure mineral ions and water is
reabsorbed in the right amounts
Hot day with little water intake = little urine
(concentrated)
Dialysis
•Much more readily
available
•Enables you to lead
relatively normal life
•No risk of rejection
•No need for medicine
Transplant
•Eat what you like
•Lead a normal life
•Free from restrictions
which come with regular
dialysis sessions
•Rejection & availability?
The Respiratory System:
-O2 diffuses into your
bloodstream and CO2 diffuses out.
-Alveoli=large surface area,
efficient blood supply, thin walls.
- Inhalation = diaphragm
contracts, ribs move up and out,
more space in chest cavity,
reduced air pressure, air drawn
into lungs
Sports Drinks:
Contain water,
ions, and glucose
Replace glucose
used in respiration
Replace water and
ions lost in
sweating
Diffusion
Osmosis
Active
Transport
Movement of...
Liquid/gas
particles
Water
Solutes
(minerals/ions)
Concentration
gradient
High → Low
High → Low
Low → High
Energy?
No
No
Yes
Membrane?
Not essential
Partially
permeable
Yes, with
carrier protein
Animal
example
O2 across
alveolus
Water in/out
of cell
Villi &
absorption
Plant example
Gas exchange
@ stomata
Guard cells,
root hair cell
Root hair cell
The Blood
WHITE BLOOD CELLS
PLATELETS- help blood to clot
PLASMA- holds dissolved
substances, CO2, waste products
(e.g. urea from the
kidneys)
RED BLOOD CELLS- No
nucleus- more room for
Haemoglobin. Large surface area
to absorb O2
HAEMOGLOBIN- substance
which gains oxygen from the
lungs to form OXYhaemoglobin.
Then releases oxygen into cells.
The Intestine
VILLI= tiny protrusions in the intestine which help to absorb the products of digestion
Use active transport + diffusion to gain as much of the valuable materials, especially
sugar, as possible
Adaptations of villi (AND ALVEOLI):
- Have a large surface area (squashed up)
- Are very close to a large network of capillaries (absorbed straight into blood stream)
- Thin wall
The Circulatory System:
Circulatory system = blood vessels,
heart and blood.
lungs
Humans have a double circulatory
system. Heart = pump.
3 main types of blood vessel:
Arteries (Away from heart), veINs
(INto heart) and capillaries.
Valves ensure correct direction of
blood flow
Arteries have thick muscular & elastic
walls (narrow lumen/interior).
body’s
cells
Artificial ‘stents’ can help keep
arteries from narrowing
Keywords: Transpiration, artery, vein, capillary, heart, red blood cells, haemoglobin, plasma, platelets, an/aerobic respiration,
Keywords: Biogas, biofuels, mycoprotein, insulin, glucagon, glucose, glycogen, vasodilation
Transpiration is the loss of water by
evaporation from plants.
Plants lose water when they open the
stomata in the leaves to let in carbon
dioxide (controlled by guard cells).
Transpiration happens faster in hot,
dry, windy conditions.
Wilting - when
Type I diabetes: Not enough
more water is
insulin produced, insulin
lost than can
injected
be replaced
Type II: body not responsive
to insulin. Diet carefully
Xylem –
controlled.
transports
water & ions,
Blood sugar regulation:
roots to leaves
If high: pancreas releases
& stem
insulin, glucose → glycogen in
Phloem –
liver.
transports
If low: pancreas releases
sugars, biglucagon, glycogen → glucose
directional
Thermoregulation:
If hot: sweating (heat lost when
evaporates), hairs flat, vasodilation
(increase blood flow to skin, heat
lost through radiation).
If cold: shivering, vasoconstriction
Biogas – mainly methane – produced by
anaerobic fermentation of a wide
range of plants and waste materials
that contain carbohydrates
Gets rid of waste, solves energy needs
and is renewable, however hard to do
it on a large scale
Fermenters
Microbes can be grown on a large scale
using fermenters
Fermenters have features such as an
oxgen supply, stirrer to keep
microorganisms in suspension and
maintain an even temp, water-cooler
jacket to remove excess heat and
measuring instruments such as pH and
temperature gauges
Mycoprotein is produced by allowing the
fungus ‘Fusarium’ to grow on sugar syrup
in aerobic conditions
Food production:
Energy lost at each stage in a food
chain (due to respiration, movement
waste materials etc.).
Improving efficiency in food
production: decrease no. of stages,
limit movement, control temp.
Biofuels
Ethanol based fuels can be produced from
anaerobic fermentation of sugar cane
juices by the enzyme carbohydrase.
+Adv. = does’nt produce toxic gases, much
cleaner and can be mixed with petrol,
carbon neutral
Disadv. = needs lots of space, poor
countries grow cash crops instead of
feeding people  starvation.
Pollution:
Greenhouse gases: methane,
CO2
Water pollutants: fertilisers,
sewage, pesticides
Acid rain: sulphur dioxide,
nitrogen oxides (cars, power
stations)
Human impacts: deforestation
(loss of biodiversity), removal
of peat lands, building
Exchange in Plants
Need osmosis in
roots (for water)
and diffusion near
stomata (for CO2)
Leaves thin + flat
to increase SA for
light and a waxy
cuticle to prevent
evaporation
Root hair cells
increase SA
because of long,
thin hairs
Most minerals +
ions needed taken
through roots
Anaerobic Respiration
Your everyday muscle
movements are made possible
by AEROBIC respiration
If heart rate is increased,
blood cannot supply O2 quick
enough
Anaerobic respiration =
incomplete breakdown of
glucose, releasing less energy
Glucose  Lactic Acid (+
energy)
Lactic acid needs to be got
rid of (by reacting with O2
to form CO2 + water) =
OXYGEN DEBT
Keywords: kidney, dialysis, transplant, immunosuppressant drugs, microbes, fermentation, alcohol, bacteria, lactic acid
1. The table below shows the amounts of some substances
that are processed by the kidneys each day.
a) Calculate the amount of water filtered each day
[1mark]
2. Plant roots absorb some of their mineral
salts from the soil by active transport.
What is involved in active transport?
[4marks]
3. a) Describe the function of the pigment found in
red blood cells [2marks]
b) Calculate the % of sodium reabsorbed [1mark]
b) Explain how red blood cells are adapted to perform
their function [3marks]
Substanc
e
water
urea
sodium
Amount
filtered
56 g
25 200
units
Amount
reabsorbed
178.5 litres
28 g
25 050
units
Percentage
reabsorbed
99.2 %
50 %
Amount
excreted
1.5 litres
28 g
150
units
4. Kidney transplants can be treated or dialysis using a
kidney ‘machine’. Discuss the advantages and
disadvantages of using dialysis or kidney transplants to
keep people alive [5marks]
5. Why is glucose found in the blood but
not in the urine? Explain as fully as you can
[3marks]
6. A fresh fruit salad is made by cutting up fruits and
placing them in a bowl with layers of sugar in
between. After 2hrs the fruit is surrounded by syrup
(concentrated sugar solution).
Explain why the syrup was produced after 2hrs
[4marks]
8. The table below shows the composition of blood
entering and leaving the lungs.
Describe in detail the changes that take place as
blood passes through the lungs [3marks]
7. Oxygen is absorbed through the alveoli of the lungs.
How are the alveoli adapted to perform this function?
[3marks]
Gas
O2
CO2
Concentration in arbitrary units
Blood entering
Blood leaving lungs
lungs
40
100
46
40
1. The table below shows the economic costs and
benefits of using a particular type of biogas
generator. Using the table, discuss the adv. and
disadv. Of using this type of generator [4marks]
Feature
Cost of generator and fitting
Annual maintenance costs
Annual profit from gas produced
Annual profit from fertiliser produced
2. During exercise the process of respiration
produces excess heat. Explain how the body
prevents this heat from causing a rise in core
body temp. [4marks]
Cost or profit (£)
250
40
30
40
6. Use the table below to explain how a cactus is
better adapted to living in hot, dry conditions
[4marks]
5. Describe, in as much detail as you can, how
the body responds to an increase in blood
sugar concentration [3marks]
4. For this question write your answer on a separate
sheet. The information in the table compares two farms.
a) Use this information to work out the average daily
human energy requirement in kilojoules (kJ) per day
[2marks]
Name
Farm
A
Farm
B
Grows…
Food for
humans
Food for
animals which
are
food for us
Energy value of
food for humans
made in 1 year
3285 million kJ
No. of people whose
energy needs are
met by this food
720
365 million kJ
80
b) Explain why Farm A is much more efficient at meeting
human food energy requirements [3marks]
c) The human population has been increasing rapidly
throughout this century. It is now about 6 billion and is
still growing. What does the information in this question
suggest about likely changes in the human diet which may
need to occur during the coming century? Explain your
answer [4marks]
3. Describe the process of transpiration in plants
[3marks]
Feature
Thickness of waxy cuticle
Total leaf surface area (cm 2)
% of water storage tissue in stem
No. of stomata per mm2
Time of day when stomata open
Horizontal spread of roots (m)
Geranium
5
1800
50
59
daylight
0.2
Cactus
15
150
85
13
night
5
7. Explain, as fully as you can, how agricultural
activities are contributing to global warming
[5marks]
8. Explain why after exercise, despite sitting
down to rest, breathing rate and oxygen
consumption remain high [4]
Side 1 Mark Scheme
1..
a. 180 OR 179.9
b. 99.4
2. Molecules/ions (named example) [1], move across membrane/cell wall [1], against a concentration
gradient [1], using a carrier protein [1], requires energy [1], obtained through respiration [1]
3..
a. Carries oxygen / forms oxyhaemoglobin [1], from lungs to cells/tissues [1] OR remove carbon
dioxide [1]
b. No nucleus [1] therefore more space for oxygen [1], large surface area [1] for efficient oxygen
absorption [or similar] [1]
4. Comparison of cost (dialysis more expensive long term) [1], lifestyle restrictions e.g. diet with dialysis
[1], independent after transplant [1], low availability of transplant [1], donated kidney may be rejected /
immunosuppressant drugs required [1]
5. Glucose enters the blood from digestive system/intestine etc. [1], glucose is filtered [1], reabsorbed [1]
by active transport [1]
6. Ideas that: sugar has dissolved in moisture (on surface of fruit) [1], this solution more concentrated
than solution inside fruit [1], osmosis [1], movement of water out of fruit [1], through partially permeable
membrane (of fruit cells) [1]. any four for 1 mark each; allow explanations in terms of concentrations of
water molecules for full marks
7. Large surface area [1], thin walls [1] therefore short diffusion distance [1], highly vascularised / good
blood supply etc. [1]; all to maximise efficiency of gas exchange [1]
8. Oxygen more concentrated in blood leaving the lungs [1], 2.5x more [1]; carbon dioxide more
concentrated in blood entering lungs [1], 1.125x more [1] (allow converse arguments)
Side 2 Mark Scheme
1.Advantages (max 3): reduced use of fossil fuels [1], less smoke produced [1], cheaper long-term
[1], fertiliser produced [1], means of waste disposal [1], energy self sufficient [1]. Disadvantages
(max 3): high initial cost [1], explosion risk [1], training required [1]
2.Increased sweat production [1], evaporation cools body [1]; vasodilation [1], heat loss (by
radiation) [1]
3.Evaporation of water [1], from the leaves [1], through the stomata [1], causing a pull [1], so that
water moves up the plant [1], = transpiration stream [1], water enters through roots [1]
4..
a. 12500 [2] 1 mark for correct working if answer incorrect
b. Any three linked points from, less: links in food chain [1], energy lost at each link [1], energy
lost in respiration [1], energy used to maintain body temp. [1], energy used in movement [1]
c. People will eat more food from plants (or converse) [1]; land available for food production is
limited [1], meat will become more expensive [1], more people = less land for food production
[1], land more expensive [1], demand for food will rise [1], greater demand for factory farming
[1], farmers will need to improve efficiency [1]
5.Insulin released [1], by pancreas [1]; glucose converted to glycogen [1] in liver [1]
6.Any 4 features + explanation from: thicker cuticle to retain water [1], smaller surface area to
reduce water loss/heat absorption [1], fewer stomata and closed in day to reduce water loss [2],
widespread roots for water absorption [1], more water storage tissue [1]
7.Any five from: methane produced [1] by cattle [1] and rice fields [1]; more greenhouse gases [1],
increased CO2 from transport/machinery etc. [1], deforestation releases CO2 [1] due to burning / less
photosynthesis [1]; heat radiated from Earth is absorbed/reflected [1]
8.Need to remove extra CO2 [1], remove heat / cool down [1], anaerobic respiration has occurred [1],
lactic acid produced [1], oxygen required to breakdown lactic acid [1] into CO2 and water [1]