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Bio: CORE PRACTICALS > Topic 5 > Flashcards

Topic 5 Flashcards

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Biology 101 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?

A

Compass

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
Q

How is a line transect used?

A
  • A tape measure is placed from one point to another

- Number of each species that touch the tape measure is recorded

26
Q

How is a belt transect used?

A
  • Frame quadrats placed along all transect length
27
Q

How is an interrupted transect used?

A
  • Quadrats placed at fixed intervals along transect
28
Q

What are the 3 experiments used to investigate the effect of temperature on climate change?

A
  • Seedling growth rate
  • Brine shrimp hatch rate
  • Effect of temperature on rate of catalse breaking down hydrogen peroxide into water and oxygen
29
Q

Explain how to carry out a seedling growth rate experiment. 6

A
  • 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
Q

How do you calculate the average growth rate of the seedlings?

A

Average change in seedling height/incubation period

31
Q

Explain how to carry out the brine shrimp hatch rate

A
  • 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
Q

How can hatch rate be calculated?

A

number of hatched brine shrimp in each water bath/number of hours

33
Q

What factors need to be kept the same for the seedling growth experiment? 3

A
  • Light intensity
  • Content of soil
  • Co2 concentration
34
Q

What factors need to be kept the same for the brine shrimp hatch rate experiment? 3

A
  • Oxygen concentration
  • Volume of water
  • Salinity of water
35
Q

What enzyme breaks down hydrogen peroxide into water and oxygen?

A

Catalase

36
Q

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

A
  • 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
Q

What is the Hill reaction? 3

A
  • In light dependent reaction
  • NADP acts as an electron acceptor for the hydrolysis of water where oxygen is released
  • NADP itself is reduced
38
Q

What can be added to isolated chloroplasts to investigate rate of Hill reaction?

A

DCPIP

39
Q

Why is DCPIP added to isolated chloroplasts?

A

It also acts as an electron acceptor and gets reduced but with an observable colour change

40
Q

What is the colour change observed with DCPIP when reduced?

A

Blue to colourless

41
Q

Explain how to carry out the DCPIP experiment: stage 1, obtaining chloroplast pellets [9]

A
  • 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
Q

Explain how to carry out DCPIP experiment: stage 2, measuring light absorbance

A
  • 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
Q

What are the variables that need to be kept the same for the DCPIP experiment? 2

A
  • Distance from lamp

- Amount of time exposed to lamp

44
Q

How can light intensity affect on Hill Reaction be measured?

A

Vary distance of test tubes away from lamp

45
Q

What is in the isolation medium in the DCPIP experiment? 3

A
  • Sucrose
  • Potassium chloride
  • Phosphate buffer at pH 7
46
Q

Why is sucrose in the isolation medium?

A

To prevent water drawn up into chloroplasts by osmosis

47
Q

What 2 negative control tubes should be set up for DCPIP experiment?

A
  • 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
Q

Instead of a quadrat what would you use for flying insects?

A

A sweepnet

49
Q

Instead of a quadrat what would you use for ground insects?

A

Pitfall trap

50
Q

Instead of a quadrat what would you use for aquatic animals?

A

A net

Bio: CORE PRACTICALS (9 decks)

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