BIOLOGY JOURNAL: Practical

Stage 2: Testing Ideas

"Do mealworms prefer the smell of vinegar or the smell of air"

Aim of experiment: To find out if mealworms prefer the smell of vinegar or the smell of air?

Hypothesis: The mealworms will prefer the smell of air

Materials:

-1 clear plastic tube

-1 clear plastic tube with vinegar infused cotton ball

-stopwatch

-6 mealworms

Procedures:

1) Place 3 mealworms in the clear plastic tube

2) Place 3 mealworms in the clear plastic tube with vinegar infused cotton ball.

3) Start the stopwatch

4) Wait for 10 mins then stop the stopwatch

5) Observe reactions of the mealworms

6) Record your observations down!

Variables:

Independent- Presence/Absence of vinegar

Dependent- Reaction of mealworm

Constant- Temperature of surrounding air

Observations: The mealworms in the clear plastic tube with vinegar infused cotton ball wanted to escape but the mealworms in the clear plastic tube made no indications that it wanted to move away.

Collect, Record & Interpret Data: On moodle

What are some assumptions made?:

Collabrated with Guo Bo Hui:

http://bohui106biology.blogspot.sg/

List the characteristics of living things
List the conditions needed to support life
Discuss with your group how you would carry out experiment to find out whether these unknown substances are actually living things.

Which characteristics of the living things are you using in your experiments?
How would you carry out the experiment?
What kind of evidence will you collect to show it is living?
From the evidence can you infer that it is a living thing?

All answers found here: http://goo.gl/g35sa

Physical Appearance of Substances A, B, C, D & E:

Substance A:

Sandy

Substance B:

Yellowish in colour

Substance C:

Crystal-like; Water-Baby

Substance D:

Seed-like

Substance E:

Brownish; powdery

Why were these liquids chosen (Water, Glucose, Salt Water)?

I guess they were used to trigger some changes in the substances. It is also according to how much reaction they will cause the substances to have.

Table #1: Observation of Substance A, B, C, D, E in Water:

Substances	Physical Appearance	Appearance at 0 min	Changes observed after 10 mins	Inference/Evidence of life
A	Uneven Particles; Sandy	Some substance sank to the bottom of the test tube and some dissolved. Water turned murky.	Slightly cloudy; particles sinking	No evidence of life
B	Particles are long; Yellowish	Milky; Cloudy	Almost all substances dissolved in the water; Water turned milky	No evidence of life
C	Crystal-like; Circular; Transparent	Remain the same; substance at the bottom	Substance expanded in size; Water remained transparent	Living things grow
D	Seed-like; Roundish	Some floating at the bottom	Substance sprouted some yellow; Water remained transparent.	Living things grow
E	Brownish powdery like	Particles floating with clumps on top & below	Some floating; some in the middle; some sank	No evidence of life

Table #2: Observation of Substance A, B, C, D and E in Glucose

Substances	Appearance at 0 min	Changes observed after 10 mins	Inference/Evidence of life
A	Some substance sank to the bottom of the test tube and some dissolved. Water turned murky.	Slightly cloudy; particles sinking	No evidence of life
B	Milky; Cloudy	Almost all substances dissolved in the water; Water turned milky	No evidence of life
C	Remain the same	Substance expanded in size; Water remained transparent	Living things grow
D	Some sinking at bottom	Substance sprouted some yellow; Water remained transparent.	Living things grow
E	Particles clump together on top & below	Some floating; some in the middle; some sank	No evidence of life

IMAGES:

Substance A at 0 min

Substances A and B at 0min (left to right)

Substances C and D at 0min (left to right)

Substance E at 0min

Substances A, B and C after 10min (left to right)

Substances D and E after 10min (left to right)

All images from:

http://parkjiwon24106biologyjournal.blogspot.sg/

Table #3: Observation of Substance A, B, C, D and E on Wet Cotton Wool

Substances	Changes observed after 10 mins	Changes observed after 24 hr	Changes observed after 36 hr	Inference/Evidence of life
A	Substance remained grainy and brown.	Substance remained grainy and brown.	Substance still remained grainy and brown.	No evidence of life
B	Substance appears as creamy coloured liquid.	Substance appears as creamy coloured liquid	Substance still appears as creamy coloured liquid	No evidence of life
C	Substance expanded in size	Substance appears even larger	The size of the substance is the biggest among the three timings.	Not sure
D	Substance sprouted some yellow things.	Sprouted some more yellow things.	Yellow stuff became green	Living things grow
E	Substance remained brown and powdery.	White things appeared in between the substance.	More white things appeared.	Living things respond to changes