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?
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) |
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| 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 |
IMAGES:
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