GCSE 1.2-1.7 and 2.1-2.6 Flashcards
1
Q
Describe all parts of a light microscope
A
Ocular lens Body tube Revolving nosepiece Low, medium and high power objectives Arm Stage clips Stage Diaphragm Lightsource Coarse adjustment knob (big) Fine adjustment knob (small) Base
2
Q
What magnification does the eyepiece lens give
A
X10
3
Q
What magnification does each objective lens give and what is the total
A
Low - X4 so total = X40
Medium - X10 so total = X100
High - X40 so total = X400
4
Q
What is the purpose of iodine and methylene blue on your temporary mounts (onion slide)
A
To stain the cells/structures and make them visible under light
5
Q
Why must the onion tissue be 1 cell thick? What happens if you have more than one layer?
A
If it is more than one cell thick it will be too hard to see an individual cell as the light can’t reach the top layer
6
Q
Why is it important to only use the fine focus when viewing at high power?
A
As it may resulting in crashing into the slide if coarse is used
7
Q
What happens to the area of the specimen you can see as you increase magnification
A
You see it closer and therefore more detail
8
Q
What are the seven process which are common to all living things
A
Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition
9
Q
What is something made of a large number of cells
A
Multicellular
10
Q
What are organism described as when only made up of one cell
A
Unicellular
11
Q
What does a nucleus do
A
Contains all the chemical reactions that take place inside the cell
Contains all the genetic information needed to produce a new living organism. It is bound by a nuclear membrane
12
Q
What do chromosomes do
A
Found within nucleus
Made of DNA
Consist of many genes which control the organisms characteristics
13
Q
What is a mitochondria
A
Free in Cytoplasm
The site of cell respiration
The more energy required by a cell, the more mitochondria will be present within it eg muscle and sperm cells
14
Q
What is cytoplasm
A
A jelly like substance with hundreds of chemicals in it
Lots of chemical reactions take place in it
15
Q
What is a cell membrane
A
A think skin around the cell, holding the cell together
Provides a barrier, and controls what passes in and out of the cell
As only some substances can cross this membrane it is described as selectively permeable
16
Q
What is a cell wall
A
Lies outside of cytoplasm
Made of cellulose
Provides a ridged support and so gives the plant cell a particular shape
17
Q
Name all the parts in a plant cell
A
Cytoplasm Cell wall Cell membrane (2 lines) Mitochondria Vacuole Chloroplasts Nucleus Nuclear membrane
18
Q
Name all the parts in an animal cell
A
Cytoplasm Mitochondria Cell membrane Nucleus Nuclear membrane
19
Q
What is a large permeable vacuole
A
Fluid filled space surrounded by a membrane
Contains cell sap, made up of water, minerals and dissolved substances
Keeps the shape of the cell, when full, and keeps the cells rigid giving the plants more support
20
Q
What are chloroplasts
A
These are present in plant cells which photosynthesise
Contain a green substance called chlorophyll that trap light energy and help the plant make its own food by photosynthesis
21
Q
Name the parts of a bacterial cell
A
Cell wall Cytoplasm Bacterial DNA (chromosomal DNA) Plasmid DNA Flagellum
22
Q
Give the light microscope equation
A
Total magnification = magnification of objective lens x magnification of eyepiece lens
23
Q
What is the magnification triangle
A
O
M A
O = observed size A = actual size M = magnification
24
Q
A nucleus in a photograph, magnification X400, measures 15mm. What is its actual size in um
A
A=O/M = 15/400 = 37.5 um
25
How much is 1000 um in mm
1mm
26
How much is 1000mm in m
1m
27
How much is 1m in um
1,000,000um
28
If a cell measures 1.3mm what is its length in um
1300
29
If a cell measures 27.5um what is its length in mm
0.0275mm
30
Give some facts about electron microscopes
Use an electron beam instead of light, which is focussed using electromagnets
Specimen has to be specially prepared and held inside vacuum chamber from which the air has been pumped out
Image is formed as photograph (electron micrograph)
Very large pieces of equipment that require special rooms in a laboratory
31
Resolution of a light microscope
0.20um
32
Resolution of an electron microscope
0.25x10 to the power of -3um
33
Magnification using light microscope
Up to X1500
34
Magnification using electron microscope
Up to X500,000
35
Give some specialised animal cells
Sperm cell
Ciliates epithelial cells
Nerve cells
36
Give some specialised plant cells
Root hair cells
Onion epidermical cells
Plant leaf palisade mesophyll cells
37
Cells to organism flow chart
Cells -> tissue -> organ -> organ system -> organism
38
What forms a tissue
Group of specialised cells working together
39
What forms an organ
Tissues working together
40
What forms an organ system
Organs working together
41
What forms an organism
Organ systems working together
42
Define diffusion
The random movement of molecules from an area of high concentration to an area of low concentration, down a concentration gradient
43
What is net movement
Overall movement
44
Give an example of diffusion of gases
Oxygen required for respiration passes through gas exchange surfaces eg alveoli by diffusion. The carbon dioxide produced by respiration diffuses in the opposite direction
45
Why is smoke visible coming out of a chimney but becomes invisible very quickly
It disperses in air. High concentration of soot particles which diffuse into surrounding air becoming dispersed and appearing invisible
46
What are stem cells
Cells which are undifferentiated and have not yet become specialised
47
What are the 2 important abilities stem cells have
To continue dividing by cell division to produce more stem cells
To differentiate into a wide variety of specialised cells
48
Where can stem cells be harvested from
Umbilical comes of babies immediate after birth
Placenta of babies immediately after birth
Early human embryos that are not used in fertility treatments
49
Give an example of stem cells being used in medicine
Bone marrow transplants in treating Leukaemia
50
Digestive organs
Mouth, stomach, small + large intestines
51
Respiratory organs
Trachea, bronchi, lungs
52
Skeletal organs
Ribs and bones
53
Circulatory organs
Heart + blood vessels
54
Excretory organs
Liver, kidneys, + bladder
55
Nervous organs
Brain + spinal cord
56
Reproductive organs
Testes + ovaries
57
Main organs in plants
The root
The stem
The leaves
The flower
58
Describe where stem cells occur in plants
In the meristems of plants
59
Word equation for photosynthesis
Carbon dioxide + water -light energy-chlorophyll-> glucose + oxygen
60
Balanced chemical equation for photosynthesis
6CO(2) + 6H(2)O -light energy-chlorophyll-> G(6)H(12)O(6) + 6O(2)
61
Describe the parts of a leaf
```
Very top - wax cuticle
Top chunk - upper epidermis
Middle chunk - mesophyll
Upper middle - palisade mesophyll
Lower middle - spongy mesophyll
Bottom chunk - lower epidermis
Gap - stoma
Bits before gap - guard cell
```
62
Give some adaptations of the leaf for light absorption
```
Thin leaves
Learned surface area
Cuticle
Upper epidermis
Palisade mesophyll layer
Chloroplasts
```
63
What are endothermic reactions
reactions which require or absorbs energy from its surrounding, usually in the form of heat
64
What is a better way of measuring the rate of photosynthesis than counting bubbles
Bubbles could be different sizes so should measure volume of oxygen produced
65
What happens in the light intensity graph of rate of photosynthesis
It goes up and plateaus
66
What happens in the time of day graph of rate of photosynthesis
At 00:00 it start going up
| At 12:00 it peak and dips down again for 24:00
67
What happens in the carbon dioxide concentration graph of rate of photosynthesis
Goes up and then keeps going up very vey slightly
68
What happens in the termperature graph of rate of photosynthesis
Goes up really high then goes all the way down
69
What are the limiting factors in the light intensity graph of rate of photosynthesis which has the letters A, B and C and 2 lines based on higher and lower CO2
A - Light intensity
B - carbon dioxide
C - Temperature
70
How is maximum heat achieved in a green house
Paraffin heaters
Artificial light
Water sprinklers
Fertilisers
71
Give the word equation for respiration
Glucose + oxygen -> water + carbon dioxide + energy
72
Whenever both respiration and photosynthesis are equal what is it called
Compensation point
73
Explain why raising light intensity increases the rate of photosynthesis
As light is an essential part of photosynthesis
74
What is a heat shield
A heat shield means there is only one source of heat.
75
When are compensation points
Dawn and dusk
76
Describe photosynthesis and respiration during the day
Both photosynthesis and respiration occur
At high light intensity (midday) - the rate of photosynthesis is greater than the rate of respiration
Therefore the net movement is CO2 enters and O2 exits the leaf
77
Describe photosynthesis and respiration at night
There is no light for photosynthesis
Respiration still occurs
So O2 enters the leaf and CO2 leaves it
78
Describe photosynthesis and respiration at low light intensity (dawn and dusk)
The rate of photosynthesis slows down and is equal to the rate of respiration. This is the compensation point. Therefore overall there is no gas exchange as:
The CO2 produced in respiration is used for photosynthesis
the O2 produced in photosynthesis is used for respiration
79
How can the movement of carbon dioxide and oxygen into and out of plants be determined
Using hydrogen carbonate indicator
80
Give the three colours of hydrogen carbonate indicator and why
Red in normal atmospheric carbon dioxide levels
Yellow in increased carbon dioxide levels
Purple in decreased carbon dioxide levels
81
What are the main factors of photosynthesis and crop production
```
Temperature
Carbon dioxide levels
Light intensity
Mineral availability
Water availability
```
82
Which factor limits photosynthesis on a bright winter afternoon in a British grassland
There will be enough light and carbon dioxide therefore temperature is likely to be limiting
83
What factor is limiting photosynthesis in a cornfield in mid summer sunshine in southern France
There will be enough light and temperatures will be high. Carbon dioxide is likely to be the limiting factor
84
On a graph with Y axis (rate of photosynthesis) what are the limiting factors at A, B and C
A - light intensity
B - temperature
C - carbon dioxide
85
Why do thin leaves help light absorption
The short distance from the top of a leaf (cuticle) to the bottom (lower epidermis) allows all the cells to receive light
86
Why does a large surface area help light absorption
Enables the leaf to absorb maximum sunlight onto its surface
87
Why do cuticles help light absorption
This is thin and transparent so doesn’t prevent light entering, but is also a waxy layer so also reduces water loss by evaporation. It is a physical defence mechanism
88
Why does a palisade mesophyll layer help light absorption
Contains many tightly packed and regular shaped palisade cells that are rich in chloroplasts near the surface of the leaf to obtain maximum sunlight
89
What does the upper epidermis do to help light absorption
Cell walls are a physical defence for leaf against microbes, and are transparent to allow light to pass through
90
What do chloroplasts do to help light absorption
Contain the pigment chlorophyll to absorb sunlight
91
What does a spongy mesophyll layer do to help gas exchange
The cells have fewer chloroplasts and are irregularly shaped resulting in a large surface area for gas exchange. There are many air spaces within this layer
92
What do intercellular air spaces do to help gas exchange
These occur in the spongy mesophyll and allow the movement of oxygen and carbon dioxide through the leaf
93
What do guard cells and stomata do to help gas exchange
Carbon dioxide and oxygen can enter and leave through the stomata. Stomata are small pores that occur between the guard cells. These guard cells regulate the opening and closing of stomata. There are more stomata non the underside of a mesophytic leaf to prevent water loss. In many plants stomata are open during the day but closes at night
94
How did the leaf change when placed in boiling water - what has happened and why
When placed I’m boiling water the plant was softened and killed as the temperature was so high. It also allows chemicals to enter
95
How did the leaf change when it was placed in boiling ethanol - why is this an important step
When placed in boiling ethanol all of the chlorophyll came out
96
In the experiment finding out if chlorophyll is needed for photosynthesis what colour changes occur to the leaf and why
Only the green parts of the variegated leaf contained chlorophyll and so they reacted with the iodine and turned blueblack. The areas without chlorophyll are unable to produce starch so they do not turn blueblack
97
How is a plant destarched
Leave in a dark place for a period of time
98
Why is a plant destarched
To prevent photosynthesis
99
How much starch can be stored in a plant
Unlimited as it is insoluble and so doesn’t upset the water balance of the cells.
99
What can glucose be turned into in a plant
1. Sucrose and carried to other parts of the plant
2. Glucose for respiration or active transport
3. Starch and stored
4. Glucose combines with nitrates to become amino acids which are made into protein - a vital building block for plant cells involved in growth and repair
5. Lipids for storage in seeds
99
Why is glucose turned into lipids in seeds
Lipids are insoluble and contain twice as much energy as the same weight of starch, thus enabling storage of more energy in a small space.
99
How do you adapt the elodea test to show how light intensity, carbon dioxide and temperature affects the rate of photosynthesis
Light intensity- by moving a desk lamp further away at pre determined intervals from the pond weed
Carbon dioxide - by adding more spatulas of hydrogen carbonate indicator to the water
Temperature - by adding warm water to the experiment and recording the temperature with a thermometer
99
Why is it necessary to take 5 minutes before taking measurements in the elodea test
Need plant to get ready for new conditions and get used to it (plant needs to equilibrate to new conditions)
99
How is the rate of photosynthesis calculated in the elodea test
Count bubbles given off by plant in set period of time
99
What are the 5 limiting factors of photosynthesis
1. Light
2. Chlorophyll
3. Carbon dioxide
4. Water
5. A suitable temperature
99
What are the types of carbohydrates
Simple carbohydrates are called sugars eg glucose, lactose.
| Complex carbohydrates are built from many sugar molecules joined together eg cellulose, starch and glycogen
99
What is starch
Starch is a polysaccharide built from a chain of glucose molecules joined together
99
What is a glucose
Glucose is a monosaccharide. Respiration provides the body with energy using glucose as a raw material
99
How much energy does 1g of carbohydrate, fat or protein
1g of Carbohydrate or protein = 17kJ
| 1g of fat = 38kJ
99
What are proteins
These are the building blocks for the growth and repair of cells. They can be used for energy when stores of carbohydrate and lipids are low. They are made from long chains of amino acids.
100
What breaks down proteins in pot amino acids
Protease
101
What breaks down starch into glucose
Amylase
102
What breaks down fats (lipids) into glycerol and then fatty acids
Lipase
103
What are lipids (fats)
Lipids consist of a molecule of glycerol linked to 3 fatty acids. Fats are energy stores. Fat layers are also good insulation
104
What reagent is used with starch and what are the initial and positive final colours
Reagent - iodine
Initial colour - yellow/brown
Positive colour - blue/black
105
What reagent is used with sugar and what are the initial and positive final colours
Reagent - Benedict’s reagent
Initial colour - blue
Positive colour - green - brick red precipitate
106
What reagent is used with protein and what are the initial and positive final colours
Reagent - biuret solution
Initial colour - blue
Positive colour - purple
107
What reagent is used with fat and what are the initial and positive final colours
Reagent - ethanol
Initial colour - clear
Positive colour - white emulsion
108
What is the equation used to work out the energy in 1g of food
Energy released form food per gram (J) = (mass of water (g) X temperature rise (degrees C) X 4.2) / mass of food sample (g)
109
Name some factors which could affect the amount of energy needed for a person
Size, activity, age, gender, pregnancy, growing child
110
Place the following carbohydrates in order of number of units contained starting with the smallest
Glycogen Glucose Lactose
Glucose Lactose Glycogen
111
Give one example of a functional protein in a cell
Hormones
112
Which 3 elements are in carbohydrates, fats and proteins
Carbon, hydrogen and oxygen
113
Which additional element is found on proteins
Nitrogen
114
What are the properties of sugars
C H O
| 6 12 6
115
What is an enzyme
All enzymes are proteins. Enzymes are biological catalysts which speed up the rate of reactions without being used up in the process
116
What does the statement ‘enzymes are substrate specific’ mean
This means that each enzyme will only react with certain substances
117
What is the optimum pH or optimum temperature
The pH or temperature at which an enzyme works best at
118
What is denaturation and how does it happen
Denaturation is when an enzyme is broken and cannot function properly. An enzyme is denatured at either very Hugh temperatures or extremes of pH
119
What are the 4 things that affect the rate of an anthem controlled reaction
1. The concentration of the enzymes
2. Th concentration of the substrate
3. The pH
4. The temperature
120
What happens to enzymes at low temperatures
1. Decreased kinetic energy
2. Particles move around less and are less likely to collide
3. Less collisions means a slower reaction
121
What happens to enzymes when the temperature is increased
1. Increases kinetic energy
2. They move around faster and are therefore more likely to collide
3. Move collisions means more reactions as some must fit
4. Reaches optimum temperature- maximum rate of reaction
122
What happens to enzyme activity when the enzyme concentration is increased
1. Increased number of enzymes
2. More free active sites to fit into
3. More likely something will collide and be broken down
4. Increases rate of reaction
123
What are the 5 important properties of enzymes
1. They’re all proteins
2. Can be used again and again
3. Catalyses one reaction
4. Influenced by temperature
5. Influenced by temperature
124
What is respiration
Respiration is the release of energy from food
125
What is the energy released in respiration used for
1. Growth
2. Movement
3. Reproduction
4. Active transport of materials
5. Heat
126
What is the aerobic respiration word equation
Glucose + oxygen = energy + carbon dioxide + water
127
What is the balanced aerobic respiration equations
(C)6(H)12(O)6 + (6O)2 = energy + (6O)2 + (6H)2(O)
128
What are the two types of respiration
Aerobic and anaerobic
129
What happens in the muscles when anaerobic exercise occurs
1. Lactic acid is produced
| 2. Much less energy released
130
What is the word equation for anaerobic respiration
Glucose = lactic acid + small amount of energy (150kJ)
131
What is anaerobic respiration
The release of energy from food without oxygen
132
Is there a link between level of fitness and breathing rate
The fitter you are the less your breathing rate
133
Is there a link between level of fitness and recovery time
The fitter you are the faster your recovery time
134
How does the body get rid of lactic acid
The oxygen oxidises the lactic acid
135
What is yeast used in
1. Beer and wine
| 2. Baking
136
What is the word equation for anaerobic respiration in yeast
Glucose = alcohol + carbon dioxide + small amount of energy
137
What are the similarities between aerobic and anaerobic respiration
1. Energy is released by breakdown of sugar
2. ATP made
3. Some energy lost as heat
4. CO2 is produced
138
What are the differences between aerobic and anaerobic respiration
Aerobic - uses O2, no alcohol/lactic acid made, large amount of energy
Anaerobic- does not use O2, lactic acid in made in humans and alcohol in yeast, small amount of energy
139
What is the path of air in the body
Nasal cavity - trachea - 2 bronchi - many bronchioles - many alveoli
140
Why is it better to breathe through your nose
It filters and warms the air before it reaches your lungs
141
Why is the trachea held open by a ring of cartilage
To stop it from collapsing
142
What is in between the ribs and lungs
Pleural fluid
143
What are some respiratory surfaces in the body that are adapted
Large surface area in the lungs - many alveoli in each lung and large surface area means more gas exchange
Thin wall with shirt diffusion distances
Moist walls help gases pass through respiratory surfaces because the gases dissolve in the moisture
Permeable surfaces - the moist thin walls make the respiratory surfaces permeable
The alveoli are surrounding by capillaries to ensure any oxygen diffusing is carried around the body
The process of breathing ensures that there is a large diffusion gradient that encourages oxygen to diffuse into the blood and carbon dioxide to diffuse into the alveoli
144
What is ventilation
The movement of air into and out of the lungs
145
What happens when you inhale
Intercostal muscles contract, rib cage moves up and out, diaphragm contracts and moves down, volume in thorax increases, air pressure in chest decreases and air moves in
146
What happens when you exhale
Intercostal muscles relax, rib cage moves down and in, diaphragm relaxes and moves down, volume in throat decreases, air pressure in chest increases and air moves out
147
Name the elements that are in inspired air
21% oxygen
0.04% Carbon dioxide
78% nitrogen
A little bit of water vapour
148
Name the elements that are in expired air
16% oxygen
4% carbon dioxide
78% nitrogen
A lot of water vapour
149
What colour does bicarbonate indicator and limewater turn when in the presence of carbon dioxide
Bicarbonate indicator: red to yellow
| Limewater: clear to cloudy
150
What does the balloons, thin sheet of rubber and plastic tube represent in the model of the lungs
Balloons are the lungs
Thin sheet of rubber is the diaphragm
Plastic tubes are the trachea and bronchi
151
Name 3 differences between the model lungs and real lungs
1. In a human the ribs work with the diaphragm to change the volume of the thorax but the model lung only shows the diaphragm
2. In real lungs the diaphragm is a dome shape not a flat like in the model lungs
3. The space between the lungs and chest wall is a lot greater in the model
152
What must all respiratory surfaces be/have
1. Be well supplied with air/blood/water
2. Be moist
3. Have a large surface area
4. Be permeable and be thin
5. Gave a diffusion gradient for gases
153
What is gas exchange
Gas exchange is the exchange of gases across a respiratory surface eg oxygen is taken in and carbon dioxide is removed
154
Name the parts of the physical parts of a Central Nervous System diagram
Brain
Skull
Vertebrae
Spinal cord
155
What are the two main parts of the central nervous system
1. Brain
| 2. Spinal cord
156
What are the three main parts of the peripheral nervous system
1. Sensory neurones
2. Association neurones
3. Motor neurones
157
Give the flow chart for nerves
Stimulus -> receptor -> brain -> effector -> response
158
What are the 3 types of neurone
1. Sensory
2. Association
3. Motor
159
What is a nerve impulse also known as
An electrical impulse
160
What are synapses
Small gaps between neurones à Roos which impulses jump
161
What happens at a synapse
1. A neurotransmitter chemical produced in on neurone, is released from vesicle
2. The chemical diffuses across the synapse and attaches to receptors on the next neurone
3. If there is a high enough concentration of neurotransmitters, it will trigger an electrical impulse in the next neurone
162
What are voluntary actions
They are responses to stimuli which you can choose to do or not to do
163
What are involuntary actions
These happen whether we want them or not. We cannot make them happen or stop happening. They occur in our bodies all the time. We have no conscious control over them
164
What are reflex actions
A reflex is an automatic immediate response to a particular stimulus by means of a nervous pathway involving a small number of nerve cells
165
What does the spinal cord contain
Dark central grey matter, white matter and the central canal
166
What does the central canal contain
Cerebrospinal fluid
167
What does dark central grey matter contain
It contains mainly cell bodies and synapses
168
What does white matter contain
It Contains long nerve fibres which run up and down the spinal cord, connecting with many reflex arcs and the brain
169
What are effectors
They are the structures in the body that carry out the response to a given stimulus eg the elbow joint
170
What are antagonistic muscles
Opposing muscles
171
Where is a transmitter substance found in relation to neurones
In vesicles
172
Name all the parts of the eye
Conjunctiva, cornea, iris, pupil, lens, aqueous humour, ciliary muscle, suspensory ligament, vitreous humour, optic nerve, Sheath of nerve, fovea, retina, sclera
173
What happens to the lens when looking at something distant
The lens is made thinner high makes it bend light rays less
174
What happens to the lens when looking at something close
The lens is made fatter which makes it bend light rays more
175
How are rays of light bent after they enter the cornea
They are bent inwards (refracted) because is a converging lens
176
Where are light rays refracted to in the eye
The retina
177
What is the ciliary muscle
It is a ring of muscle that surrounds the lens of an eye
178
How is the lens attached to the ciliary muscle
By suspensory ligaments
179
What are the ciliary muscle and suspensory ligaments like
Ciliary muscles are like an elastic band, while the ligaments are like a piece of string
180
What is ecology
Is the study of the interaction between living organisms and their environment
181
What is the environment
Means all the conditions that surround any living organism - both the other living things and the non living things or physical surroundings
182
What is a habitat
Means a place where plants and animals live
183
What is a population
Means all the members of a single species that live in a habitat
184
What is an ecosystem
Is a community of plants, animals and micro-organisms, together with the habitat where they live
185
What is a niche
Is the role of a living organism within a community
186
What is biodiversity
Is the measure of the different types of plant and animal species in an area
187
What does biotic mean
This is the term used to describe the living components of the environment
188
What does abiotic mean
The non living parts of the environment that might relate to the climatic factors like temperature, light intensity and humidity
189
What name is given to a large range of sampling techniques
Field work
190
What are two major aspects of sampling
Ensuring the data is reliable and representative
191
How do ensure the data is reliable when sampling
Through taking results from many different sampling points and then calculating an average value. The more samples that are taken, the more reliable the results
192
What does representative mean in terms of sampling data and how do you ensure the data is representative
This simply means that what is recorded is a true reflection of what is actually in the environment. To ensure results are representative sampling points must be random. This ensures that bias does not influence the results
193
What is a quadrat
A quadrat is a simple frame (usually 0.5m x 0.5m) that can be placed on the ground in order to sample a specific area of ground cover
194
When using a quadrat what measurement us used
When using a quadrat the percentage cover is often estimated. It is not possible to record specific values of percentage cover so in most cases percentage cover values would be 1%, 10%, 20% and so on up to 100%
195
What is a belt transect
A belt transect is a technique used when there is gradual change from one habitat to another
196
How is a belt transect carried out
In a belt transect, quadrats are placed along a line end on end allowing a strip of the ground and the species growing on it to be sampled. As the transect progresses from one end to another the numbers of certain species will decrease whilst others will increase
197
Name some abiotic factors that an influence what types of organisms can survive in a habitat
```
Wind speed
Water content of soils
The pH of soils
Light intensity
Temperature
```
198
How is wind speed measured and how can it influence what types of organisms can survive in a habitat
Wind speed can be recorded using an anemometer. This factor can influence the types of species present for example in sand dunes and also in mountain ranges. The values of wind speed can indicate how exposed a certain habitat is.
199
How is the water content of soils measured and how can it influence what types of organisms can survive in a habitat
In ecological investigations soil samples can be collected and returned to the lab. Weighing the soil and then drying out until the mass stays constant which allows the percentage water content to be estimated. The water content of soils can influence what types of organisms can survive in a habitat as plants need a ready supply of water to survive. For this reason sandy soils that don’t retain much water tend only to support a small number of highly adapted plants
200
How is the pH of soils tested and how can it influence what types of organisms can survive in a habitat
The pH of a soil can be tested chemically using a soil sample and universal indicator or simply by inserting a pH probe into the ground. The pH of soils can affect what types of plants grow there as some plants prefer acidic soils, whilst others have a preference for alkaline conditions
201
How is light intensity measured and how can it influence what types of organisms can survive in a habitat
Light intensity is easily measured using a light meter. Light intensity can greatly affect the distribution of plants. If plants are shaded by taller trees they will probably have adaptations to allow them to absorb a greater amount of the available light
202
How is temperature measured and how can it influence what types of organisms can survive in a habitat
Temperature is readily measured using a soil thermometer. Temperature is a further factor that can influence distribution of organisms
203
What is a competition in terms of ecology
Competition in ecosystems refers to the need for organisms to obtain resources from the habitat in which they live.
204
Name four things plants compete for
1. Water
2. Light
3. Space
4. Minerals
205
Name four things animals compete
1. Food
2. Territory
3. A mate
4. Shelter
206
Why are animals adapted to their environment
Usually there is not enough of the given resource for both organisms and therefore the organism that is better suited will obtain more of that resource and its chances of survival are greater.
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What is a organism called that makes its own food and makes energy available to the rest of the food
A producer eg a plant
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Where do plants obtain their energy from
Plants obtain their energy from the sun during the process of photosynthesis
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What are all animals
Consumers
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What are the 3 classes of consumers
1. Herbivores
2. Carnivores
3. Omnivores
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What are primary consumers
Animals that feed on plants
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What are secondary consumers
Animals that feed on the primary consumer
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What are tertiary consumers
Animals that feed on secondary consumers
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How is a food chain arranged
The organisms involved are assigned to a stage in the chain based on how they obtain their food. These stages are referred to as trophic levels
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What trophic level are plants always at
The first
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What trophic level is the primary consumer at
The second
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What trophic level are the secondary consumers at
The third
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What trophic level are tertiary consumers at
The fourth
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What do the arrows on a food chain represent
The flow of energy
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What is a food web
A collection of food chains
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Why don’t food chains contain more than 3 or 4 trophic levels usually
This is because energy is lost at each stage in the food chain
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Is photosynthesis efficient for absorption of energy
This process is very inefficient with only a small amount of light energy actually hitting the plants gets absorbed by chlorophyll as most is reflected or passes through the leaf
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How much energy is lost every stage of the food chain
Around 90%
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Name 4 ways energy is lost in the food chain
1. Not all of the available materials is eaten
2. Much of the food is not digested
3. The process of excretion
4. All organisms respire and lose energy as heat
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What is a pyramid of numbers
The numbers of organisms at each trophic level represented in the form of graph
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Why are pyramids of number not always the best representation of feeding relationship
They do not consider the size of the organisms at each trophic level
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How is the issue of a pyramid of numbers fixed
It is inverted then represented in biomass
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What happens to the nutrients when an organism dies
Even if an organism dies, the nutrients it contains will eventually be released back into the ecosystem in the form of various minerals and other nutrients found in the soil
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Whilst energy _____; nutrients ____
whilst energy flows; nutrients cycle
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What are the two process involved in nutrient cycling
1. Decay
| 2. Decomposition
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Give an example of the process of decay
Various small animals such as worms and insects break down dead organisms as they feed on them
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What is referred to as extra cellular digestion
The bacteria and fungi digest the materials by releasing (secreting) enzymes from their cells onto the decayed material. These enzymes break the molecules down into a more soluble form that the bacteria and fungi then absorb. This mode of digestion is sometimes referred to as extracellular digestion
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What is known as saprophytic nutrition
When extracellular digestion is used to complete the breakdown of dead material
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What is a major product of the decay and decomposition process
Humus
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What are the 3 conditions required for a effective decay and decomposition
1. Warm temperature
2. Moisture
3. A large surface area
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What is the carbon cycle
A nutrient cycle that shows how carbon is passed from the atmosphere into plants and on to animals as they feed on plants. The cycle also includes the processes of decomposition, combustion and fossilisation.
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What is combustion
When any fuel is burnt it releases carbon in the form of carbon dioxide back into the atmosphere.
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What is fossilisation
under certain circumstances dead organisms do not become fully decomposed. Over millions of years these partially decomposed materials are converted into fossil fuels such as coal, oil and gas.
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What 3 problems can increasing temperatures cause on the earth
1. Melting ice caps leading to increased sea levels
2. Climate change
3. Loss of habitats
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What does the nitrogen cycle show
How nitrogen gas is converted into nitrogen containing compounds in plants and animals and then how the nitrogen these compounds contain is recycled either back into the air or made available to other organisms
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Why is the nitrogen cycle important
It is important as it shows how organisms obtain their amino acids and proteins which are required for growth
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Where is the Nitrogen fixing bacteria found
found living in the soil as well as in the root nodules of a specific group of plants called leguminous plants
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Why is the Nitrogen fixing bacteria important
The nitrogen fixing bacteria in the root nodules provide the plant with all the nitrates required for making amino acids and proteins. In return the plant provides the bacteria with a ready source of carbohydrates - these are required to allow the bacteria to respire
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What is nitrification
A process that converts ammonia and other nitrogen containing ions in the soil into nitrates that can be readily absorbed by plant roots
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What is Denitrification
the process that converts nitrates back into nitrogen gas. This is an undesirable process as it results in less nitrate being available in the soil and therefore reduced plant growth
246
Ow are root hair cells adapted and why are they adapted
They are adapted by having an increased surface area due to the presence of an extension of their cell walls. They are adapted in order to absorb minerals and water from the soil
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What is active uptake
This is a process that moves materials from a region of low concentration to a region of higher concentration against the concentration gradient
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What process is needed to occur for active uptake to happen
Respiration
