lab quiz 1

Question 1

phytophages

Answer 1

leaf eating insects

Question 2

frugivores

Answer 2

fruit eating insects

Question 3

Monarch butterfly

Answer 3

feeds on milkweed. Produces milky sap which acts as skin irritant. Monarch butterflies consume this plant and then are poisonous to birds that eat them

Question 4

Simple random sampling

Answer 4

pooling all groups together and choosing number… for leaf experiment could have ended up with 15 leaves from tolmie and 5 leaves from uvic

Question 5

Stratified random sampling

Answer 5

dividing into groups first… then randomly selecting from those groups

Question 6

3 ecological issues concerning the effects of herbivory

Answer 6

1) Herbivores at controlled levels vs outbreak levels
2) effects of herbivores on primary productivity
3) what factors control herbivores? ex. plant chemistry, food quality, defense chemicals etc.

Question 7

pseudoreplication

Answer 7

• treating samples that are not independent as independent samples… decreases validity
• measuring leaves on trees, want to have an estimate population at each position… 2 leaves from the same trees and averaging isn’t good

Question 8

What does the confidence interval mean if it does not include 0

Answer 8

means there is a difference

Question 9

What does it mean if the p-value is less than the alpha value

Answer 9

-there is evidence to reject Ho and lend support for Ha

Question 10

what does an alpha value of 0.05 mean

Answer 10

means that the p-value would have a 5% chance of error

Question 11

Pros of stratified random sampling?

Answer 11

-controls for other variables

Question 12

Cons of stratified random sampling

Answer 12

• when researchers can’t classify every member of a population into a subgroup
• overlapping: when subjects fall into multiple subgroups

Question 13

Pros simple random samling

Answer 13

-easy and accurate

Question 14

cons simple random samplihgn

Answer 14

• pools all the numbers… samples that are way out of the normal range will deviate the results a lot…
• doesn’t control for variables so much

Question 15

what are gary oaks named after?

Answer 15

Nicholas Gary

Question 16

Where trees are Gary oaks found around

Answer 16

1) arbutus

2) Douglas Fir

Question 17

why is variation in a trait important

Answer 17

for its ability to evolve thru natural selection

Question 18

how is the mean value useful

Answer 18

1) sometimes the best representation of a population

2) the mean can be used for comparing populations or samples

Question 19

What did Darwin say the reason for differences between species was

Answer 19

said that the differences we observe between species may arise from variation in properties within a species

Question 20

A bar graph of the numbers of whelks in each size class is called a ________

Answer 20

size frequency distribution

Question 21

what does a larger aperture size mean in whelks? and why?

Answer 21

larger foot… this is an adaptation to wave action

Question 22

What does a bigger foot mean in whelks

Answer 22

greater power of adhesion and therefore a whelk from a more exposed habitat should have a larger foot

Question 23

as predation pressure increases… what happens to the whelks

Answer 23

whelks will have thicker shell

Question 24

Different between transect and quadrat sampling

Answer 24

transect- any line marked at regular intervals

quadrat - framed area

Question 25

how to calculate shell aperture index

Answer 25

Ia = [ (∏ (L+w/4)^2)/h ]

Question 26

main factors that influence whelk morphology: sheltered vs. exposed habitat

Answer 26

Sheltered: predators
Exposed: Wave action

Question 27

Positively skewed data

Answer 27

Shampoo example: several caps were tightened much harder than they should be

Question 28

What does it mean when error bars overlap?

Answer 28

While the means APPEAR to be different, the difference is probably not significant

Question 29

Interval Bar

Answer 29

a vertical bar with horizontal endpoints of the 95% CI for the mean

Question 30

Standard error bar

Answer 30

a vertical line with horizontal endpoints at one or multiple standard errors

Question 31

Main difference between bar charts and histograms

Answer 31

the x-axis of bar charge represents a “categorial” variable. The x-axis on a histogram represents a continuous, “quantitative” variable

Question 32

Skewness and symmetry of…

Answer 32

you can only talk about skewness or symmetry of histograms… that is the tendency of observations to fall more on the low or the high end of the x-axis.

Question 33

when is a scatterplot used

Answer 33

when you have bivariate data (2 variables)

Question 34

What does linear regression attempt to do

Answer 34

attempts to model the relationship between the data

Question 35

Difference between line and point transects

Answer 35

line transects- recording of data is continuous

point transects- recording of data occurs at regular intervals and for a given duration at each point

Question 36

why are transects good

Answer 36

they are highly adaptable and efficient

Question 37

Random transect approach

Answer 37

starting points and directions at random

Question 38

Stratified random approach

Answer 38

starting points and directions at random BUT where each lies within an individual habitat stratum

Question 39

What are quadrants most appropriately used for

Answer 39

sessile animal or plant populations

Question 40

What do you have to decide before using quadrants

Answer 40

1) the # of quadrats
2) the size of the quadrants
3) the placement of the quadrats