Skip to content / Đến nội dung
ThichHocToan.com

PIMSO 2022 - Science - Grade 8 - National Round

Question 1

Organisms adapt according to their environment and needs through the process of natural selection. Beaks of birds are especially adapted to a specific diet and lifestyle. The following images are beaks belonging to birds that are found in the Philippines. Which beak belongs to a grain-eating bird?

Question illustration

Editorial scope: select the conventional conical grain-cracking bill; the source does not identify the species.
  1. Image a
  2. Image b
  3. Image c
  4. Image d
  5. Image e

Question 2

The following image shows Amoeba proteus. Which of the following statements is not true regarding this protozoan?

Question illustration
  1. It is unicellular.
  2. It moves by ciliary extensions.
  3. It feeds by phagocytosis.
  4. It reproduces by binary fission.
  5. None of the above.

Question 3

Unlike in spermatogenesis where mature spermatozoa are produced from primary spermatocytes, oogenesis is only completed upon fertilization by the spermatozoa. In which stage of the meiosis is the oogenesis halted before fertilization?
  1. Prophase I
  2. Anaphase I
  3. Prophase II
  4. Metaphase II
  5. Telophase and Cytokinesis II

Question 4

Polydactyly is an anomaly characterized by the presence of extra fingers or toes and is genetically inherited among families. The graph below is a pedigree analysis of the proband (red) who has polydactyl. What is the pattern of inheritance of polydactyly in the proband’s family?
Reference: Wang et al., Scientific Reports 6, 38500 (2016).

Question illustration
  1. Autosomal dominant
  2. Autosomal recessive
  3. X-linked dominant
  4. X-linked recessive
  5. Y-linked

Question 5

Which of the following plant tissues play a role in the transport of food and water?

Question illustration
  1. Image a
  2. Image b
  3. Image c
  4. Image d
  5. Image e

Question 6

Immunoglobulins, also known as antibodies, are produced upon vaccination or infection of the SARS-CoV-2, to neutralize the virus and prevent further infection. All of the following statements therefore describe the mechanisms by which immunoglobulins neutralize the SARS-CoV-2, except one. Which one is not?

Editorial review: distinguish direct viral neutralization from other antibody-mediated immune mechanisms.

Original choices:
A. Immobilization of the virus
B. Blocking the viral entry into the cell
C. Opsonisation and phagocytosis of the virus
D. Promote inflammation to fight the virus
E. Trigger the lysis of virus-infected cells

Question 7

Which of the following elements would you expect to gain an electron when forming a chemical bond?
Shown below is a Periodic Table for reference:

Question illustration

Editorial convention: interpret “an electron” as exactly one electron to complete the outer shell in the simple octet model.
  1. C
  2. N
  3. O
  4. F
  5. Ne

Question 8

Which of the following is NOT true?
  1. An element may exist with different isotopes and ionic forms
  2. Ions of the same element always has the same number of neutrons
  3. Elemental atoms having different number of electrons are different ionic forms
  4. Isotopes of an element have the same number of protons
  5. None of the above

Question 9

The table below shows the properties of different liquids A to D:
Liquid; Color; Density (g/ml); Boiling Pt (°C); Other properties
A; Blue; 1.05; 95; Hydrophobic
B; Green; 1.06; 73; Hydrophilic
C; Red; 1.21; 80; Hydrophilic
D; Yellow; 0.82; 60; Hydrophobic
Which of the following illustrates the best way to layer the liquids?

Question illustration

Editorial review: examine both density ordering and whether four separate phases are established.

Original choices:
A. Image a
B. Image b
C. Image c
D. Image d
E. None of the choices

Question 10

Biofuels are sources of energy from renewable sources. One example is bioethanol, which is ethanol (C2H6O) sourced from fermentation of plant products. In one experiment, 1.00 g of liquid ethanol was found to burn with 2.08 g of gaseous oxygen. Like most hydrocarbons, this combustion process produces water (H2O) and gaseous carbon dioxide. The experimental setup allowed a student to recover 100 % of the water produced from this reaction but not all of the gaseous carbon dioxide. What would be the total weight of products the student can expect from his experiment?

Editorial review: distinguish products formed from products recovered, preserving the duplicated choices.

Original choices:
A. Less than 2.08 g
B. Exactly 3.08 g
C. Less than 3.08 g
D. Exactly 3.08 g
E. Cannot be determined from the given information

Question 11

Which of the following elements would you expect to be the least reactive?
  1. Si
  2. P
  3. S
  4. Cl
  5. Ar

Question 12

One forefront in the development of environmentally-friendly automobiles is the search for new fuels from renewable sources. In 2008, the airplane manufacturing company Boeing tested a small aircraft powered by a hydrogen fuel cell. In this fuel cell, hydrogen is reacted with oxygen, producing water, as a source of energy. Which of the following is true?

Terminology note: interpret “addition” here in the source’s broad combination/synthesis sense.
  1. This decomposition reaction produces energy
  2. This addition reaction is exothermic
  3. This decomposition reaction is endothermic
  4. This decomposition reaction is also a combustion reaction
  5. None of the above

Question 13

A container ship left Manila Bay at 5:00 am. The following graph shows the distance it travelled during the first five seconds of the trip. The data was graphed and was found to follow the trend d=3t² where v is the distance and t is the time. Which of the following best describes its acceleration?

Question illustration

Editorial correction: use d for distance, as shown by the vertical axis; assume motion in one direction.
  1. Acceleration is changing at 3 m/s²
  2. Acceleration is constant at 3 m/s²
  3. Acceleration is constant at 1.5 m/s²
  4. Acceleration is constant at 6 m/s²
  5. Acceleration is changing at 1.5 m/s²

Question 14

Complete the following sentence about light: Decreasing the _____ of light results in higher energy.

Editorial scope: compare the energy per photon in vacuum.
  1. Frequency
  2. Wavelength
  3. Amplitude
  4. Velocity
  5. Focus

Question 15

The Maria Christina Falls is a 98 m waterfall in northern Mindanao in the Philippines. Aside from being known for its natural beauty, it has been harnessed for hydroelectric power.
Assuming that water from the top of the falls contains only potential energy, at what speed would any mass of water drop at the bottom of the falls? (Assume a simplistic model in which no water from the bottom recoils and affects the speed of the falling mass of water.)

Question illustration
  1. 9.8 m/s
  2. 13.9 m/s
  3. 21.9 m/s
  4. 30.9 m/s
  5. 43.8 m/s

Question 16

Which of the following soundwaves show the lowest pitch?

Question illustration
  1. Image a
  2. Image b
  3. Image c
  4. Image d
  5. Image e

Question 17

Which of the following is NOT an acceptable report of the length of the following circuit board given the limited precision of the ruler?

Question illustration

Editorial scope: compare precision under the one-estimated-digit classroom convention, not the accuracy of every listed value.
  1. 24 mm
  2. 25 mm
  3. 24.5 mm
  4. 24.75 mm
  5. 25.0 mm

Question 18

Aside from the capital Manila, two other major cities in the Philippines are Cebu and Davao. It is possible to travel between these two cities by a combination of land and sea travel. One may take a 6-hour bus from Davao city to Agora, Cagayan de Oro. Then, a ferry boat running at 26.67 km/hr from this port to Cebu would take 9 hours. If the average speed of the total trip is 36 km/hr, what is the speed during the land travel?
  1. 30 km/hr
  2. 40 km/hr
  3. 50 km/hr
  4. 60 km/hr
  5. 70 km/hr

Question 19

The earth’s axial tilt or obliquity continuously changes within a 40,000-year cycle, varying between 22.1 and 24.5 degrees. As the tilt becomes greater, what effect does it have in our seasons?
  1. Summers become warmer and winters become less cold
  2. Summers become less warm and winters become colder
  3. Summers become warmer and winters become colder
  4. Summers become less warm and winters become less cold
  5. Summers become more frequent while winters occur less

Question 20

These are land areas that drain rainfall and snowmelt to outflow points such as reservoirs and the ocean.
  1. Delta
  2. Watershed
  3. Peninsula
  4. Wells
  5. Loess