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PIMSO 2025 - Science - Senior Secondary - National Round

Question 1

What cell theory states that mitochondria and chloroplasts are each derived from the uptake of bacteria forming a symbiotic relationship with their host cell?
  1. Endosymbiotic Theory
  2. Germ Theory
  3. Miasma Theory
  4. Symbiotic Theory

Question 2

Which is NOT true about the comparison between Prokaryotes and Eukaryotes?

A. Prokaryotes and eukaryotes differ in size.
B. They differ in the presence of a membrane-bound nucleus.
C. Prokaryotes and eukaryotes have similar containment in DNA arrangements.
D. Prokaryotes are organisms consist of a single prokaryotic cell while Eukaryotes are organisms containing multicellular eukaryotic cells.

Editorial task: assess the alternatives and justify whether a unique answer exists.

Question illustration

Question 3

Which is NOT true about Meiosis?
  1. It happens in germ cells.
  2. Its genetic variation does not change.
  3. Its purpose is for sexual reproduction.
  4. Its chromosome number is half in each daughter cell.

Question 4

Which is NOT a stage of Mitosis?

Interpretation note: use the broad classroom convention that groups nuclear division and cytokinesis within the mitotic phase.
  1. anaphase I
  2. cytokinesis
  3. prophase
  4. telophase

Question 5

The methanogenic bacteria are a large and diverse group that is united by these features EXCEPT:
  1. They are strict anaerobes.
  2. They are members of the domain Archaea, or archaebacteria.
  3. They are classified as halophiles and thermophiles.
  4. They form large quantities of methane as the major product of their energy metabolism.

Question 6

Mark and Jane are teenagers who are conscious about their pimples because although not life-threatening, pimples are acne that can persist for years and is known to have serious psychosocial effects such as decreased self-esteem, depression, frustration, and social withdrawal among them. What causes this acne?
  1. Escherichia coli
  2. Mycobacterium tuberculosis
  3. Propionibacterium acnes
  4. Streptomyces coelicor

Question 7

The simplest formula of a substance shows:
  1. The actual number of atoms of each element in one molecule of a substance.
  2. The elements that make up one molecule of the substance and the simplest whole number ratio between the atoms.
  3. The number of molecules in a sample of the substance.
  4. The molecular mass of the substance.

Question 8

How do carbons atoms form may organic compounds?
  1. By attracting other elements toward themselves to form the bonds
  2. By forming may bonds with other carbon atoms and other elements
  3. By sharing their electrons with other metal elements
  4. By transferring their electrons to the atoms of surrounding elements

Question 9

Why do atoms react with one another to form chemical bonds?
  1. to attain stability
  2. to form compounds
  3. to form molecules
  4. to produce ions

Question 10

Fatty acids are carboxylic acids with long hydrocarbon chains attached to a carboxylate group. How does a saturated fatty acid differ from an unsaturated fatty acid?
  1. The hydrocarbon chain in an unsaturated fatty acid contains one or more multiple bonds.
  2. The hydrocarbon chain in a saturated fatty acid contains one or more multiple bonds.
  3. The hydrocarbon chain in an unsaturated fatty acid contains no more than one multiple bonds.
  4. The hydrocarbon chain in an unsaturated fatty acid contains no double or triple bond.

Question 11

How do colloidal dispersions differ from true solutions with regard to dispersed particle size and homogeneity?

A. Colloidal dispersions consist of particles that are much smaller than the average molecules and cannot scatter light.
B. Colloidal dispersions consist of particles that are much bigger than the average molecules and are big enough to scatter light.
C. Colloidal dispersions consist of particles that are much bigger than the average molecules but not big enough to scatter light.
D. Colloidal dispersions consist of particles that are on the microscopic scale, thus appearing homogeneous but are big enough to scatter light.

Editorial task: assess the alternatives and justify whether a unique answer exists.

Question 12

If you fill a glass to the brim with ice water and the ice melts, what will happen?

Assume pure ice floats freely in pure water; ignore evaporation, thermal expansion and dissolved substances.
  1. The glass will over flow as the ice turns to water.
  2. The level of water in the glass will remain unchanged as the ice melts.
  3. The water level will drop slightly as the ice melts.
  4. I will never find out because I will drink the water or walk away before anything happens.

Question 13

Observe the graph below and check how the changes in position of the three athletes displays their displacement. Answer the questions that follow. Which of the athletes has travelled the longest at 20 minute-time interval?

Question illustration

Interpretation note: compare total distance over the displayed 5–20 minute record only; no motion before 5 minutes is specified.
  1. Athlete 1
  2. Athlete 2
  3. Athlete 3
  4. Both B and C

Question 14

An ambulance is hurriedly running in a highway due to an emergency and its siren emits soundwaves at a frequency of 100 KHz. An SHS student standing in the highway perceives the sound of the siren at 250 KHz as the ambulance approaches but perceived it to be 80 KHz as it moves away. This phenomenon is called ______?
  1. Doppler Effect
  2. harmonics
  3. interference
  4. superposition

Question 15

What conclusion can be derived from the diagram below?

A. Silver has greater density than gold.
B. Gold has greater density than Silver
C. A silver cube should have a greater volume to have the same mass as gold
D. A Gold cube should have a greater volume to have the same mass as silver

Editorial task: assess the alternatives and justify whether a unique answer exists.

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Question 16

A large truck passes a car on the highway. According to Bernoulli's principle, which of the following will occur?
  1. Pressure decreases between the vehicles, so the car and truck move slightly apart.
  2. Pressure increases between the vehicles, so the car and truck move slightly apart.
  3. Pressure increases between the vehicles, so the car and truck move slightly together.
  4. Pressure decreases between the vehicles, so the car and truck move slightly together.

Question 17

Given the diagram below, what characteristic of electric fields inside conductors can be derived?

A. Electric fields are strongest along the most curved surface.
B. Excess charges exist in the outer surface of the conductor.
C. Electric fields are directed perpendicular to the surface of the conducting object
D. If an object has reached electrostatic equilibrium, there is no parallel electric field component

Editorial task: assess the alternatives and justify whether a unique answer exists.

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Question 18

Circuits can have several power sources. Which of the following circuits has a battery source?

Question illustration
  1. Circuit A in the figure
  2. Circuit B in the figure
  3. Circuit C in the figure
  4. Circuit D in the figure

Question 19

What particles make up an atom?
  1. Protons and Neutrons
  2. Protons and Electrons
  3. Neutrons and Electrons
  4. Protons, Neutrons and Electrons

Question 20

Which of the following is TRUE about geothermal energy?

A. Geothermal energy is owned by the local environment.
B. The initial costs associated with a geothermal power plant are low.
C. There is no risk of hazardous substances during drilling.
D. A geothermal power plant can be placed almost anywhere.

Editorial task: assess the alternatives and justify whether a unique answer exists.