AP Biology Sample Student Responses and Scoring Commentary

2017

AP Biology

Sample Student Responses

and Scoring Commentary

Inside:

• Free Response Question 1

• Scoring Guideline

•

Student Samples

•

Scoring Commentary

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AP®

BIOLOGY

2017

SCORING

GUIDELINES

Question

1

TABLE 1. EFFECT OF

0.1

mM

CAFFEINE ON MEMORY IN BEES

Memory

(average probability of revisiting a

nectar

source

±

)

Treatment

10

Minutes

24 Hours

Control 0.72 ± 0.09

0.41±0.07

Caffeine 0.83 ± 0.07 0.78 ± 0.08

In flowering plants pollination

is

a

process

that

leads

to

the

fertilization of

an

egg

and

the

production of seeds.

Some flowers

attract

pollinators,

such

as

bees,

using

visual

and

chemical cues.

When

a

bee

visits a flower,

in

addition to transferring pollen,

the

bee

can

take

nectar

from

the

flower

and

use

it

to

make

honey

for

the

colony.

Nectar

contains sugar,

but

certain plants also

produce

caffeine

in

the

nectar. Caffeine

is

a bitter-tasting

compound

that

can

be

toxic

to

insects

at

high

concentrations. To investigate

the

role of caffeine

in

nectar, a

group of researchers

studied

the

effect of

0.1

mM

caffeine

on

bee

behavior.

The

results of

an

experiment

to

test

the

effect of caffeine on

bees

' memory of a

nectar

source

are

shown

in

T

ab

le 1.

(a)

On

the

axes

provided,

construct

an

appropriately labeled

graph

to illustrate

the

effect of caffeine

on

the

probability of

bees

revisiting a

nectar

source

(memory). (3

points)

Construct

graph

(3

points)

•

Correctly

plotted

means

on

a

bar

graph/modified

bar

graph

•

Appropriate

labels, units,

and

scaling

•

Correctly

plotted

error

bars

(b)

Based

on

the

results,

describe

the

effect of caffeine on

each

of

the

following:

(2

points)

•

Short-term

(10 minute)

memory

of a

nectar

source

•

Long-term (24 hour)

memory

of a

nectar

source

Description

(2

points)

Short-term

Caffeine

does

not

affect

short-term

memory

/ memory

at

10

minutes.

Long-term

Caffeine improves/incre

ases

the

long-term

memory/memory

at 24 hours.

(c)

Design

an

experiment

using

artificial flowers

to

investigate

potential

negative

effects of

increasing

caffeine concentrations

in

nectar

on

the

number

of floral visits by bees.

Identify

the

null hypothesis,

an

appropriate control

treatm

ent,

and

the

predicted

results

that

could be

used

to

reject

the

null hypothesis.

(3

points)

The

College Board.

Visit

the

College Board on

the

Web. www.collegeboard.org

2SE

X

AP®

BIOLOGY

2017

SCORING

GUIDELINES

Question

1

(continued)

Identification

(3

points;

1

point

per

row)

Null

hypothesis

Increasing

caffeine

concentration

has

no

effect

(on

the

number

of floral

visits

by

bees).

Control (Nectar/flowers

with)

no

caffeine

Predicted

results

•

The

number

of

fl

ora

l

visits

by

bees

is

different

at

increa

si

ng

caffeine

concentrations.

•

The

number

of floral

visi

ts

by

bees

is different

than

the

control.

(d)

Researchers

found

that

nectar

with

caffeine

tends

to

have

a lower

sugar

content

than

nectar

without

caffeine. Plants

use

less

energy

to

produce

the

caffeine

in

nectar

than

they

do

to

prod

uce

the

sugar

in

nectar.

Propose

ONE

benefit

to

plants

that

produce

nectar

with

caffeine

and

a lower

sugar

content.

Propose

ONE

cost

to

bees

that

visit

the

flowers of

plants

that

pro

duce

nectar

wi

th

caffeine

and

a lower

sugar

content.

(2

points)

Proposed

plant

benefit

(1

point)

•

More

pollen is

transferred/more

visits

by

pollinators.

•

Plants

store

energy/have

more

energy

available for

other

uses.

Proposed

bee

cost

(1

point)

•

(Individual)

bees

visit

more

flowers.

•

(Individual)

bees

use

more

energy.

•

The

colony/bees

may

produce

less

honey

•

The

colo

ny/bees

may

produ

ce

lower

quality

honey

/ ho

ney

that

prov

ides

less

ene

rgy.

The

College Board.

Visit

the

College Board on

the

Web. www.collegeboard.org

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AP

®

BIOLOGY

2017 SCORING COMMENTARY

Question 1

Overview

This question was based on investigations of the effects of caffeine on memory in bees. Caffeine is often

produced by plants in their nectar, and researchers studied the effect of caffeine on the probability of bees

remembering and, therefore, revisiting a nectar source. Students were presented with a data table indicating

the average probability of bees revisiting caffeinated and caffeine-free (control) nectar sources after 10

minutes and after 24 hours. The data included inferential error bars to compare groups. Students were asked

to construct an appropriate graph based on the data provided. Students were then asked to describe the

effect of caffeine on the short-term (10 minute) and long-term (24 hour) memory of a nectar source. Next,

students were asked to design an experiment using artificial flowers to investigate potential negative effects

of increasing caffeine concentrations in nectar on the number of floral visits by bees. As part of their

experimental design, students were asked to identify the null hypothesis, an appropriate control treatment,

and the predicted results that could be used to reject the null hypothesis. Finally, students were told that

nectar with caffeine often has a lower sugar content than nectar without caffeine, and plants expend less

energy to produce caffeine than to produce sugar. Based on this information, students were asked to propose

one benefit to plants that produce nectar with caffeine and to propose one cost to bees that visit the flowers

of the plants that produce nectar with caffeine.

Sample: 1A

Score: 10

T

he r

esponse earned 1 point in part (a) for correctly plotting the means on a bar graph. The response

earned 1 point in part (a) for appropriate labels, units, and scaling. The response earned 1 point in part (a)

for correctly plotting the error bars. The response earned 1 point in part (b) for describing the effect of

caffeine on the short-term (10 minute) memory of a nectar source as having no significant effect. The

response earned 1 point in part (b) for describing that long-term (24 hour) memory was significantly

improved by caffeine. The response earned 1 point in part (c) for identifying the null hypothesis as varying

caffeine concentrations in nectar will not affect floral visits by bees. The response earned 1 point in part (c)

for identifying that the control group was without any caffeine. The response earned 1 point in part (c) for

identifying that the greatest concentration of caffeine would yield a lower number of floral visits by bees

than the control solution as the predicted results. The response earned 1 point in part (d) for proposing that

one benefit to plants is using saved energy to support other aspects that will improve survival/reproductive

rates. The response earned 1 point in part (d) for proposing that one cost to bees is decreased efficiency

because flying around plants uses energy.

Sample: 1B

Score: 8

The response earned 1 point in part (a) for correctly plotting the means on a bar graph. The response

earned 1 point in part (a) for appropriate labels, units, and scaling. The response earned 1 point in part (a)

for correctly plotting error bars. The response earned 1 point in part (b) for describing the effect of caffeine

on the short-term (10 minute) memory as not being statistically significant. The response earned 1 point in

part (b) for describing that caffeine increases the long-term memory of a nectar source. The response

earned 1 point in part (c) for identifying that the control would be artificial flowers with no caffeine. The

response earned 1 point in part (c) for identifying that changing the concentration of caffeine will not affect

the number of floral visits by bees as the null hypothesis. The response earned 1 point in (c) for identifying

that if bees revisited flowers with high concentrations of caffeine significantly more than the flowers

without caffeine the null hypothesis would be rejected.

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AP

®

BIOLOGY

2017 SCORING COMMENTARY

Question 1 (continued)

Sample: 1C

Score: 6

T

he response earned 1 point in part (a) for appropriate labels, units, and scaling. The response earned 1

point in part (b) for describing that the effect of caffeine on the long-term (24 hour) memory is a large

increase in memory. The response earned 1 point in part (c) for identifying that caffeine concentration will

not affect the number of floral visits by bees as the null hypothesis (H

0

). The response earned 1 point in part

(c) for identifying an appropriate control treatment as flowers without caffeine. The response earned 1

point in part (c) for identifying that the number of floral visits by bees will be negatively affected by

caffeine concentration. The response earned 1 point in part (d) for proposing that one benefit to plants is

that the average probability of the bees revisiting the nectar source is increased with more caffeine.

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