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Bio: CORE PRACTICALS > Topic 5 > Flashcards

Topic 5 Flashcards

1
Q

What is the advantage of random sampling?

A

Avoids bias

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2
Q

How should random sampling be carried out? 2

A
  • Divide field into grid with measuring tapes

- Use a random number generator to generate coordinates to put quadrats on

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3
Q

When should non random sampling be used? 3

A
  • When there is a variety of abiotic factors
  • When there is a variety of species distribution
  • To ensure all different areas are sampled
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4
Q

How is systematic sampling carried out?

A
  • Samples are taken at fixed intervals along a line transect
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5
Q

When is systematic sampling used?

A

When abiotic factors change gradually from one end of an area to another - an environmental gradient

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6
Q

What is a frame quadrat used for?

A

Immobile populations

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7
Q

What is a frame quadrat?

A

A square frame divided into a grid of 100 smaller squares by strings attached across the frame

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8
Q

For larger trees and plants what can be used instead of frame quadrats?

A

Large quadrats created with tape measures

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9
Q

What are point quadrats used to investigate?

A

Plant populations when there is dense vegetation close to the ground

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10
Q

What is a point quadrat?

A

A horizontal bar on 2 legs with holes in set intervals along its length

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11
Q

How are point quadrats used to investigate populations?

A
  • Placed on the ground at random points
  • Pins dropped through holes in the frame
  • Every plant touching each pin is recorded
  • Number of individuals in each species recorded in each quadrat
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12
Q

List abiotic factors that can be investigated

A
  • Temperature
  • Humidity
  • Solar input/light intensity
  • Rainfall
  • Oxygen availability in water
  • pH of soil
  • Moisture content of soil
  • Relief
  • Slope angle
  • Aspect
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13
Q

What is temperature measured with?

A

Thermometer

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14
Q

What is humidity measured with?

A

Electronic hygrometer

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15
Q

What is rainfall measured with?

A
  • A rain gauge - a funnel attached to a measuring cylinder

- Measure a volume of water collected over a period of time

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16
Q

How is soil pH measured? 2

A
  • Using indicator liquid

- Electronic pH monitor

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17
Q

How is oxygen availability measured in aquatic habitats?

A

Oxygen sensor

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18
Q

How is solar input/light intensity measured?

A

Light sensor

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19
Q

What is relief?

A

How the height of the land chances across a surface

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20
Q

How can relief be measured?

A

Take height readings using GPS device at different points across surface

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21
Q

How can slope angle be measured?

A

Clinometer

22
Q

How can aspect be measured?

23
Q

What is aspect?

A

Direction the land is facing

24
Q

What are the 3 types of transect?

A
  • Line transect
  • Bell transect
  • Interrupted transect
25
How is a line transect used?
- A tape measure is placed from one point to another | - Number of each species that touch the tape measure is recorded
26
How is a belt transect used?
- Frame quadrats placed along all transect length
27
How is an interrupted transect used?
- Quadrats placed at fixed intervals along transect
28
What are the 3 experiments used to investigate the effect of temperature on climate change?
- Seedling growth rate - Brine shrimp hatch rate - Effect of temperature on rate of catalse breaking down hydrogen peroxide into water and oxygen
29
Explain how to carry out a seedling growth rate experiment. 6
- Plant some seedlings [same variety and age] in soil trays - Measure the height of each seedling - Ensure all other variables are the same - Leave for a period of incubation - Record change in height of each seedling - Calculate average growth rate
30
How do you calculate the average growth rate of the seedlings?
Average change in seedling height/incubation period
31
Explain how to carry out the brine shrimp hatch rate
- Put equal number of brine shrimp eggs - In water baths set at different temperatures - Ensure all other variables are the same - Record number of hatched brine shrimp in water bath every five hours - Calculate the hatch rate
32
How can hatch rate be calculated?
number of hatched brine shrimp in each water bath/number of hours
33
What factors need to be kept the same for the seedling growth experiment? 3
- Light intensity - Content of soil - Co2 concentration
34
What factors need to be kept the same for the brine shrimp hatch rate experiment? 3
- Oxygen concentration - Volume of water - Salinity of water
35
What enzyme breaks down hydrogen peroxide into water and oxygen?
Catalase
36
Explain how to carry out the experiment measuring the effect of temperature on rate of catalse breaking down hydrogen peroxide into water and oxygen - 10
- Set up boiling tubes containing same volume and concentration of hydrogen peroxide - Keep pH constant by adding equal volumes of buffer solution to each tube - Set up an upside down measuring cylinder in a trough of water with a boiling tube connected by a delivery tube - Put each boiling tube in a water bath set to a different temperature - Put another boiling tube in each water bath containing the same concentration of catalase - Wait for five minutes for the enzyme to reach the temperature - Use a pipette to add the same volume of catalase to each boiling tube - Attach bung and delivery tube - Record amount of oxygen produced every 10 seconds in first minute of reaction - Use stopwatch to measure time
37
What is the Hill reaction? 3
- In light dependent reaction - NADP acts as an electron acceptor for the hydrolysis of water where oxygen is released - NADP itself is reduced
38
What can be added to isolated chloroplasts to investigate rate of Hill reaction?
DCPIP
39
Why is DCPIP added to isolated chloroplasts?
It also acts as an electron acceptor and gets reduced but with an observable colour change
40
What is the colour change observed with DCPIP when reduced?
Blue to colourless
41
Explain how to carry out the DCPIP experiment: stage 1, obtaining chloroplast pellets [9]
- Cut a few leaves into pieces and remove rough stalks - Grind up leaf pieces using pestle and mortar with chilled isolation solution - Filter the liquid into beak through funnel lined with muslin cloth - Transfer liquid to centrifuge tubes - Centrifuge liquid at high speed for 10 minutes - Chloroplasts gather at bottom of tube in pellets - Remove liquid from top of tubes - Resuspend pellets in fresh chilled isolation solution - Store on ice for rest of experiment
42
Explain how to carry out DCPIP experiment: stage 2, measuring light absorbance
- Set up a colorimeter with a red filter and zero using cuvette containing chloroplast extract and distilled water - Set up test tube rack at set distance from bench lamp and switch on - Add a set volume of chloroplast extract to tube and set DCPIP volume and mix - Immediately take sample of mixture from tube and add to clean cuvette - Record light absorbance every 2 minutes for 10 minutes - Repeat experiment twice more
43
What are the variables that need to be kept the same for the DCPIP experiment? 2
- Distance from lamp | - Amount of time exposed to lamp
44
How can light intensity affect on Hill Reaction be measured?
Vary distance of test tubes away from lamp
45
What is in the isolation medium in the DCPIP experiment? 3
- Sucrose - Potassium chloride - Phosphate buffer at pH 7
46
Why is sucrose in the isolation medium?
To prevent water drawn up into chloroplasts by osmosis
47
What 2 negative control tubes should be set up for DCPIP experiment?
- Test tube with only DCPIP and isolation medium - shows DCPIP colour doesn't naturally deteriorate over time - DCIP, isolation medium and chloroplast extract wrapped in tin foil
48
Instead of a quadrat what would you use for flying insects?
A sweepnet
49
Instead of a quadrat what would you use for ground insects?
Pitfall trap
50
Instead of a quadrat what would you use for aquatic animals?
A net

Bio: CORE PRACTICALS (9 decks)

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