0
Q
Describe a natural ecosystem?
A
- natural ecosystems have BIODIVERSITY
> many different species of plants and animals coexist in the same environment
1
Q
What is an ECOSYSTEM?
A
- a physical environment with a particular set of conditions, plus all the organisms that live in it
2
Q
Describe an artificial ecosystem?
A
- e.g. Greenhouses
- designed and maintained for a particular purpose so they have low biodiversity
3
Q
What are the affects of weed killers, fertilisers and pesticides in an artificial ecosystem?
A
- they prevent other animals and plants from growing alongside the crop
- leads to low biodiversity
4
Q
Describe FORESTRY PLANTATIONS?
A
- very carefully set up, controlled and monitored.
- have less biodiversity due to the fact they aren’t as old as natural woodlands, which take years to form and result from the relationships and interactions of the organisms that live there and around.
- fewer species are introduced, and not all will survive from the start
5
Q
What is a community?
A
- the total number of individuals of all the different populations of plants and animals in a habitat at any one time
6
Q
What is a POPULATION?
A
- the total number of individuals of the same species that live in a certain area
7
Q
What is the only thing that Ecosystems rely on?
A
- their energy source, the sun
8
Q
Name 4 sampling methods used to measure the size and distribution of population?
A
- pooters
- sweep nets
- pitfall traps
- quadrats
9
Q
How do pooters work?
A
- the are containers which suck in organisms without harming them
10
Q
How do sweep nets work?
A
- used to collect insects in long grass or moderately dense woodland where there are lots of shrubs
11
Q
How do pitfall traps work?
A
Pitfall traps are containers set into ground that are used to catch small insects
12
Q
How do quadrats work?
A
Quadrats are square frames that have sides 0.5m long. They are used to count a smaller, representative part of a population.
13
Q
What must you make sure of when sampling?
A
- you take a big enough sample to make the results a good estimate
- you sample randomly, the more random the sample the more likely it is to be representative of the population
14
Q
What is Capture-recapture (Lincoln index)?
A
A method used to estimate a population size
15
Q
How does capture-recapture work?
A
1- A trap is used to catch a sample of individuals
2- the sample is counted and recorded and each individual is marked with a number tag/band or a dot of paint
3- the individuals are released, unharmed into the environment, and are given time to redistribute themselves
4- another sample is taken, some of them are marked, some aren’t.
16
Q
How can you estimate population size from capture-recapture?
A
Population size =
No. In 1st sample ✖️ number in 2nd sample
➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖
No. In 2nd sample already marked
17
Q
When using capture-recapture, what do you have to do?
A
- make sure no organisms have died, immigrated or emigrated between sampling
- make sure that identical sampling methods are used from one visit to the next
- make sure the marking of the organism doesn’t harm them
18
Q
What is a transect line used for?
A
- used to map the distribution of organisms
- used for studies of how species change across a boundary between habitats
19
Q
What is ZONATION?
A
- the gradual change in the distribution of species across a habitat
20
Q
What does photosynthesis produce?
A
- glucose for biomass and energy. Oxygen is produced as a by-product
21
Q
What is the equation for photosynthesis?
A
Carbon dioxide➕water ➡️ glucose ➕ oxygen
22
Q
What can glucose and starch be converted into?
A
- energy (during respiration)
- proteins for growth and repair
- starch, fats or oils that can be stored in seeds
- cellulose, which is needed for plant cell walls
23
Q
Describe Glucose?
A
- glucose is soluble, it can be transported around a plant as soluble sugar, but it must be converted It to starch, which is insoluble to be stored
24
Describe starch?
Starch is a very useful, strong molecule.
It is insoluble which means it doesn't affect the water concentration inside cells when stored, it also does not move away in soloutions.
25
What have scientists used radioactive oxygen-18 to discover?
- that the oxygen produced in photosynthesis as a by-product, comes from the water and not the carbon dioxide.
- only when oxygen-18 is introduced via the water do you get a radioactive waste product of oxygen.
- it shows that photosynthesis is a two-stage process.
26
Describe the two stages of photosynthesis?
1- light energy is used to split water, releasing oxygen gas and hydrogen ions.
2- then the carbon dioxide gas combines with the hydrogen to make glucose
27
How can photosynthesis be increased?
- increasing the temperature
- increasing the light intensity
- increasing the carbon dioxide concentration
28
What happens in photosynthesis when the temperature rises?
- as the temperature rises so does the rate of photosynthesis.
- this means that temperature is the limiting factor in the rate of photosynthesis.
- as the temperature approaches 45, the enzymes controlling photosynthesis start to denature and the rate of photosynthesis declines to zero
29
What happens in photosynthesis when the concentration of carbon dioxide rises?
- so does the rate of photosynthesis.
- carbon dioxide is limiting the rate of photosynthesis up to a certain point.
- after this point, a rise in carbon dioxide levels has no effect.
- carbon dioxide is no longer a limiting factor
30
What happens in photosynthesis when the light intensity increases?
- so does the rate of photosynthesis
- the light intensity is limiting the rate of photosynthesis up to a certain point, when light intensity has no further effect
31
Describe a leaf?
- contains a pigment CHLOROPHYLL, (which absorbs light) in millions of chloroplasts, plus other pigments to absorb light from different parts of the spectrum.
- is broad and flat to provide a huge surface area to absorb sunlight
- has a network of vascular bundles for support and to transport water to the cells and remove the products of photosynthesis, ie. glucose
- has a thin structure so the gases only have a short distance to travel to and from the cells
- has stomata (tiny pores) on the underside of the leaf to allow the exchange of gases; these are opened and closed by guard cells
32
What does carbon dioxide do during photosynthesis?
- carbon dioxide diffuses in through the stomata (leaf pores)
33
What does oxygen do during photosynthesis?
- oxygen diffuses out through the stomata
34
Name the four layers in a leaf?
- the upper epidermis
- the palisade layer
- the spongy mesophyll
- the lower epidermis
35
What is the upper epidermis in most leafs like?
- transparent to allow sunlight through to the layer below
36
Describe the cells in the palisade layer of a typical leaf?
- the cells are near the top of the leaf and are packed with chloroplasts so they can absorb the maximum amount of light
37
Describe the spongy mesophyll of a leaf?
- contains lots of air spaces connected to the stomata to allow the optimum exchange of gases
38
Describe plant cells?
- Plant cells contain many chloroplasts and are long so they can absorb lots of light.
- chloroplasts are are not found in all plant cells, for example in root cells, as they don't receive light
39
What is diffusion?
- the movement of a substance from a region of high concentration to a region of low concentration
40
What is random movement?
- when particles move about in lots of different directions
41
How can the rate of diffusion be increased?
- When There is a greater surface area of the cell membrane
- when there is a greater difference between concentrations
- when the particles have a shorter distance to travel
42
Describe photosynthesis and diffusion during the day?
- carbon dioxide is used up in photosynthesis. The concentration inside the leaves is lower than the concentration outside
- carbon dioxide diffuses into plants through stomata (tiny pores) on the bottom of leaves
- oxygen, a product of photosynthesis, diffuses from the plant into the atmosphere
43
What are the STOMATA on he undersides of leaves adapted for?
OPEN - to help increase the rate of diffusion of carbon dioxide and oxygen
CLOSE- to prevent excess water loss in drought conditions
44
What is Osmosis?
- the diffusion of water from high concentration of water, to a low concentration of water through a partially-permeable membrane (a membrane that allows the passage of water molecules but not solute molecules)
- a special type of diffusion involving water molecules.
- plant cells are surrounded by a membrane which allows water to move in and out of the cells
- water and solute molecules move freely through the cellulose cell wall.
45
Describe the movement of particles in Osmosis?
- the water particles move randomly, colliding with each other and passing through the membrane in both direction
- but the net movement of molecules is from the area of high water concentration to the area of low water concentration.
> this gradually dilutes the solution
46
What could happen if too much water enters an animal cell?
- the cell could burst
47
What do plant cells have that animal cells do not?
- an in elastic cell wall
48
What happens to a blood cell if it is in a pure water solution?
- it will gain water by osmosis,
- without a cell wall to prevent water entering it, they absorb more and more water until eventually they burst
This is called LYSIS
49
What happens to blood cells in a concentrated solution?
- they will lose water by osmosis
| - without a cell wall to prevent water loss, they can shrivel up and become crenated (have rough edges)
50
What does the cell wall of a plant cell do?
- prevents cells from bursting due to excess water
| - contributes to rigidity
51
What is the water pressure pushing against a plant cells wall called?
Turgor pressure
52
What happens to the plant when the pressure inside cells increases?
- the cell becomes very turgid ( rigid )
| - when all the cells are fully turgid, the plant is firm and upright
53
What do the XYLEM and the PHLOEM in vascular bundles do?
XYLEM- transports water and soluble mineral salts from the roots to the leaves
PHLOEM- allows the movement of food substances (sugars) around the plant, up and down the stems to growing tissues and storage tissues
54
Describe XYLEM vessels?
- made up of dead plant cells
- have a hollow lumen
- the cellulose cell walls are thickened with a waterproof substance
55
Describe PHLOEM cells?
- long columns of living cells
56
Describe root hairs?
- have an enormous surface area for absorbing water and so increase the plants ability to take up water
57
What is TRANSPIRATION?
- the diffusion and evaporation of water from inside a leaf.
- it causes water to be moved up xylem vessels and provides plants with water for cooling, photosynthesis and support. And brings minerals to the plant
58
Describe how the transpiration stream is powered by the evaporation of water from the leaf?
1- water evaporates from the internal leaf cells through the stomata.
2- water passes by osmosis from the xylem vessels to leaf cells, which pull the thread of water in that vessel upwards by a very small amount.
3- water enters the xylem from root tissues, to replace water which has moved upwards
4- water enters root hair cells by osmosis to replace water which has entered the xylem
59
What can the RATE of TRANSPIRATION be affected by?
- LIGHT- more light increases the rate of photosynthesis and transpiration
- AIR MOVEMENT- as the movement of the air increases, transpiration increases
- TEMPERATURE- heat increases the rate of photosynthesis and transpiration
- HUMIDITY- low humidity increases the rate of transpiration
60
Using a MASS POTOMETER, how is a leafy shoot's rate of transpiration measured?
1- the plants roots are submerged in a sealed bag of water and placed in a beaker
2- the beaker is placed on a digital balance
3- readings are taken to see how much water is lost by the plant during transpiration
4- the conditions can be changes to see how this affects the water loss
61
How do plants balance the amount of water they take in and lose?
1- water is absorbed by the plant by the root hair cells, which have large surface area to take in water
2- the water diffuses the plant up to the leaves
3- when it reaches the leaves it can be lost by transpiration
62
What adaptations do plants have that reduces the rate at which water is lost from leaves?
- a waxy cuticle on the surface of the leaf
- having the majority of the stomata on the lower surface of the leaf
- the number, position, size and distribution of stomata vary between plants depending on their environment
- the turgidity of guard cells changes in relation to the light intensity and availability if water
63
What are essential minerals to plants?
- needed to keep plants healthy and growing properly
- plants absorb dissolved minerals in the soil through their roots
- the minerals Are naturally present in the soil although they are usually of low concentration, this is why farmers use fertilisers
64
What minerals do plants need and why?
- NITRATES- to make proteins for cell growth, nitrates are used to make amino acids
- POTASSIUM COMPOUNDS- for respiration and photosynthesis, potassium is used to help the enzymes.
- PHOSPHRATES- for respiration and cell growth, make DNA and cell membrane
- MAGNESIUM- for photosynthesis, makes chlorophyll
65
What is active transport?
- when substances need to be absorbed from a low to a high concentration area
- requires energy from respiration
66
What is DECAY?
- a process involving the breakdown of complex substances into simpler ones by microorganisms.
- the key factors in the process are, microbes, temperature, oxygen and moisture
67
What can effect the rate of decay?
- CHANGING TEMPERATURE- microorganisms responsible for decay work best at around 40, slower in cooler temperatures and denature above 40.
- AMOUNT OF OXYGEN- microorganisms rate of activity increases as the amount of oxygen does. It means their rate of respiration increases which means their energy does, which means they grow faster
- AMOUNT OF WATER- microorganism prefer moist conditions, too much or too little water will affect their growth
68
Name 3 DETRITIVORES, and what they feed off and do?
1- Earth worms
2- Woodlice
3- Maggots
- feed off
> dead organisms
> decaying marital produced by organisms
- they speed up the process of decay by breaking down decaying material into small pastiches which have a large surface area, this makes it easier for decomposers (fungi and bacteria) to feed on
69
What are microorganisms used to break down?
- human waste in sewage treatment works
| - plant waste in compost heaps
70
What are SAPROPHYTES?
- they feed on Dead organic material by secreting enzymes onto the material and then absorbing the digested products
71
How can food be preserved to stop microorganisms surviving?
- sealed in sterile cans
- kept at low temperatures
- pickled, acid kills them
- preserved in sugar or salt, gets rid of wTer
- dried
72
What is intensive farming?
- methods aim to produce as much food as possible from the available land, plants and animals.
- use chemicals to kill pests that damage crops or livestock so more food is produced
73
What chemicals are used in intensive farming and why?
- PESTICIDES- used to kill pests
- INSECTISIDES- kills insect pests
- FUNGICIDES- kills fungi
- HERBICIDES- used to kill weeds which compete with crops
74
Why must care be taken with pesticides?
- they can harm other organisms
- they can build up in food chains harming the animals at the top
- some stay in the food chain for years
75
Name 4 types of intensive farming?
- battery farming
- glasshouses
- hydroponics
- fish Farming
76
What are organic farming?
- methods used to produce food without use of chemicals
77
Name types of organic farming?
- natural fertilisers
- growing nitrogen fixing crops
- rotating crops to maintain soil fertility
- avoiding chemical pesticides by weeding
- varying speed plating times
78
What are the advantages of organic farming?
- Food crops and the environment aren't contaminated
- soil erosion is limited
- biodiversity is promoted
- life stoke can move
79
What are the disadvantages of organic farming?
- it's less efficient
- organic fertilisers take longer to work
- it is expensive
- more land needed
80
What is HYDROPONICS?
- is a way of growing plants without using soil.
- the plants are grown with their roots in a solution containing the minerals needed for growth
- used in greenhouses or area with very thin or barren soil
81
What are the advantages of HYDROPONICS?
- the mineral levels added to the solution can be carefully controlled and adjusted to the type of plant
- there is a reduced risk of diseased
82
What are the disadvantages of HYDROPONICS?
- the plants have to be supported as they have no anchorage for roots
- expensive fertilisers
83
What is BIOLOGICAL CONTROL?
- when farmers introduce a predator instead of using pesticides to reduce the number of pests
84
What are the advantages of BIOLOGICAL CONTROL?
- the predator attacks the pest
- predators have long lasting impact
- the pests can't become resistant
- no need for chemicals
85
What are the disadvantages of BIOLOGICAL CONTROL?
- the pest is reduced, not removed
- the predator may not eat the pest
- the predator may leave
- the predator may reproduce out of control
Biology 4-5-6
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