Question bank IMSO Science 2006

Experiment I — The Secret of Color

I. Introduction

Look at leaves and grass: they are green. Why do some bodies look red and others blue under the same light? In sunlight, grass looks green, roofs brown and paper white. Investigate the behavior of colors.

II. Apparatus

Three light sources emitting blue, green and red; three colored screens (plates), blue, green and red; a solar cell; batteries; a multimeter adjusted to measure electric current; a static pod (stand); a ruler.

III. Method

Use the solar cell as a detector of different colored lights. Follow teacher supervision and the specified low-voltage setup; never short-circuit a battery.

III.1 Determining the color of light that has the highest energy

The source states that a solar cell produces current when illuminated, and treats the measured current as representing received light energy: greater energy gives greater current. Set up the apparatus as in Figure 1. (This simplified interpretation is examined in the explanation.)


**1.** Use the blue light source and a 6 volt battery.

**2.** Place the light source 10 cm from the solar cell.

**3.** Adjust the source so the light spot is focused at the center of the solar cell.

**4.** Record the current shown by the multimeter in microamperes.

**5.** Repeat steps 2–4 for green and red sources.

**6.** Complete Table 1 (9 points).

| Light color | Current (microamperes) |
| --- | --- |
| Blue | ____ |
| Green | ____ |
| Red | ____ |

Step 7. Which color has the highest energy? Explain your answer. (4 points)

III.2 Determining the color reflected by a colored body

Arrange the apparatus as in Figure 2 to measure light reflected by a colored screen under a specific light color.


**1.** Fix the position of the solar cell.

**2.** Select a blue source and a 9 volt battery.

**3.** Place a blue screen in position.

**4.** Record the current.

**5.** Repeat steps 3–4 for the other two plates.

**6.** Repeat steps 2–5 for the other two light sources.

**7.** Complete Table 2 (18 points).

| Light color | Plate color | Current (microamperes) |
| --- | --- | --- |
| Blue | Blue | ____ |
| Blue | Green | ____ |
| Blue | Red | ____ |
| Green | Blue | ____ |
| Green | Green | ____ |
| Green | Red | ____ |
| Red | Blue | ____ |
| Red | Green | ____ |
| Red | Red | ____ |

Step 8. Based on the table, determine which color is reflected by each colored plate. Explain your answer. (4 points)

III.3 Identifying the wiring of solar cells

The source models a solar-cell piece as a battery in series with a switch (Figure 3). Light closes the switch, allowing current; an opaque cover opens it so no current is produced. You have four pieces connected in an unknown arrangement. Determine their connections.

Arrange the equipment as in Figure 1.

**1.** Select the blue source and a 3 volt battery.

**2.** Cover the pieces in the nine combinations in original Table 3 below. Record each current.

**3.** Complete Table 3 (18 points). Black means covered and gray means uncovered. The equivalent written recording table below uses piece numbers 1–4 from left to right; the original diagram remains authoritative.

| Covered pieces | Current (microamperes) |
| --- | --- |
| 1 | ____ |
| 2 | ____ |
| 3 | ____ |
| 4 | ____ |
| 1 and 2 | ____ |
| 1 and 3 | ____ |
| 2 and 3 | ____ |
| 2 and 4 | ____ |
| 3 and 4 | ____ |

Step 4. From Table 3, draw the connections (series, parallel or a combination). Treat a current below 0.5 microampere as no current. Number the pieces according to the original numbering figure. (10 points)

IV. Designing the Solar Panel

Illuminate the solar cell with blue light at 15 cm. Record the current: ____ microamperes.

a. Calculate the number of solar-cell pieces needed to produce 10 microamperes. (5 points)
b. Calculate their total area. (5 points)

Original Figure 1, Figure 2, Figure 3, Table 3 and piece numbering follow in that order. The multimeter digits in the artwork are illustrative, not supplied measurements.

Experiment II — Human Respiration

Safety note (editorial): Do not inhale or suck through an apparatus containing limewater, and do not perform this experiment unsupervised. The historical mouth-to-apparatus instructions below are retained as source text, not a recommended procedure. A teacher should use separately collected air samples and controlled one-way gas delivery with backflow protection for a demonstration; avoid eye/skin contact and use suitable protective equipment. Any such setup is a safety adaptation, not the original apparatus or an original observation. No observation may be invented.

Materials: limewater, Ca(OH)₂.

Tools: 2 test tubes, 2 rubber stoppers, 1 T- or Y-shaped plastic pipe, 1 syringe, 1 test-tube rack, 1 timer or stopwatch.

Historical procedures (for source study only): Set up the apparatus shown below. (15 points)

Number codes in the original figure: 1 = your mouth; 2 and 3 = free air; 4 = air space in test tube A; 5 = air space in test tube B; 6 = limewater in A; 7 = limewater in B.

Prepare the test tubes and place them on the rack. Using the syringe, fill each with about 20 ml of limewater. The source says, “DON’T REMOVE THE CAP OF SYRINGE.” Close the tube mouths with rubber stoppers. This ambiguous syringe instruction is preserved, not interpreted as a safe operating instruction; a teacher must select suitable equipment.


**1.** Observe the initial condition of limewater before inhaling and blowing. Record A: ____; B: ____. (2 points)

**2.** The historical source instructs inhaling through the T-pipe “as hard as you can,” 4–5 times. Observe and record A: ____; B: ____. (2 points) Do not carry out that instruction; use the supervised safety adaptation above.

**3.** The historical source instructs exhaling (blowing) through the T-pipe “as hard as you can,” 4–5 times. Observe and record A: ____; B: ____. (2 points) Use the supervised safety adaptation instead.

**4.** Compare the limewater in both test tubes before and after inhaling and blowing. Record A: ____; B: ____. (4 points)

Answer the questions:

**1.** Trace the airflow during inhaling, using only the number codes in the original setup. (6 points)

**2.** Trace the airflow during exhaling, using only those codes. (6 points)

**3.** According to these routes, the condition of limewater will differ between A and B. Explain the difference. (6 points)

**4.** If the changes are caused by mixing or reaction between limewater and carbon dioxide, what can you conclude? (6 points)

The original apparatus drawing is preserved below for interpreting the historical questions only.

If a plant stem is cut in cross section and the xylem is distributed randomly or scattered throughout the section:

a. We can group this plant as a ____.

b. How many cotyledons does it have?

c. What kind of root system does it have?

The original cross section is shown below. No points are printed for this item; 3 points (one per part) are an editorial allocation.

An aphid sucks nutritious liquid from a plant's phloem. An ant eats sugar excreted by the aphid. Name the symbiotic relationship and explain:

a. Aphids and plants. (1 point)

b. Aphids and ants. (1 point)

Rainforest in tropical areas is the most humid area on Earth because of ____ and ____. (1 point)

The source says a squid is a cephalopod “because the animal moves by using its head.” A snail is a gastropod because ____. (1 point)

Plants make carbohydrate by photosynthesis and store it in different parts. Complete the table. (2.5 points)

| Plant | Storage part |
| --- | --- |
| Sugarcane | a. ____ |
| Potato | b. ____ |
| Carrot | c. ____ |
| Banana | d. ____ |
| Spinach | e. ____ |

Which two listed plants store carbohydrate in similar parts? ____ and ____. (0.5 point)

Fat occurs in plants and animals. In animals it is stored under the skin. In plants it is mostly stored in ____. (1 point)

Plants support life by converting light energy into chemical energy usable by other organisms. What kinds of organisms support life in the ocean in this way? (1 point)

The pictured hermit crabs use a shell for protection. When their body grows bigger, they will ____ (1 point).

a. grow the shell with their body

b. break and reform new shells

c. leave and find new shells

d. thicken and form a hard skeleton

e. undergo metamorphosis

Millions of butterflies travel from North Africa to Europe, flying about 2,000 meters high and passing across an ocean and the Alpen hills, according to the source.

What is this population movement called? (1 point)

a. transmigration; b. migration; c. mitigation; d. immigration; e. emigration.

They move from North Africa to Europe when Europe is in which season? (1 point)

a. summer; b. autumn; c. winter; d. spring.

Which statement describes the greenhouse effect? (1 point)

a. Glass buildings reflect sunlight into the atmosphere and increase its temperature.

b. We live in a greenhouse-like environment: sunlight reaches Earth's surface, but heat is reflected back to Earth by a CO₂ layer in the atmosphere.

c. Glass absorbs heat poorly, increasing atmospheric temperature.

d. Broken CO₂ and ozone layers remove the barrier to sunlight, increasing air temperature.

e. Vehicle-engine smoke is a heat source at Earth's surface; it enters the atmosphere and causes global warming.

The main aim of food preservation by sweetening, salting/pickling, heating, freezing or radiation is ____ (1 point).

a. preventing growth of food-spoilage microorganisms

b. improving taste

c. creating attractive food color

d. using bacteria for fermentation

e. protecting the original aroma

Look at the original cross section of a dicotyledon leaf.

a. Which part has the greatest role in photosynthesis? (1 point)

b. Which structure allows gas exchange? (1 point)

Plants growing in dry areas often have structural adaptations. List three such characteristics. (3 points)

The source says terrestrial plants need a sophisticated vascular system to carry water from soil to leaves, whereas aquatic plants do not. Why? (2 points)

Organisms adapt in body structure and function. Give two adaptations of animals living in cold places. (2 points)

An animal that undergoes metamorphosis has a stage valuable to humans because it produces silk thread.

a. Name the animal.

b. Name the stage of its metamorphosis. (2 points total)

Which technology imitates the sonar mechanism of bats? (1 point)

a. domestic communication satellite

b. submarine periscope

c. remote control system

d. radio control system

e. air-force radar

Keith puts a heavy rock in a plastic cup inside a glass container of water, and marks water levels on the cup and the container, as in the source drawing.

a. What happens if the rock is removed from the cup? Draw your answer. (2 points)

b. If she pushes the cup and releases it, what happens? (1 point)