1.
Long distance runners often
eat bananas the night before their competitions. Which nutrient in a banana is
important during the run?
Correct Answer
A. Carbohydrates
Explanation
Carbohydrates are the nutrient in a banana that is important during a long distance run. Carbohydrates are the body's main source of energy and are stored in the muscles and liver as glycogen. During exercise, the body breaks down glycogen to provide fuel for the muscles. Eating carbohydrates, such as those found in bananas, before a run helps to replenish glycogen stores and provides a readily available source of energy for the runner. This can help to improve endurance and prevent fatigue during the competition.
2.
The diagram below shows an unfertilised
ostrich’s egg containing a large cell.
What do the labels represent?
Correct Answer
D. Plasma membrane: Z; Cytoplasm: Y: Nucleus: X
Explanation
The correct answer indicates that the plasma membrane is represented by Z, the cytoplasm is represented by Y, and the nucleus is represented by X.
3.
Under which of these
conditions would transpiration (loss of water vapour from the leaves) be
slowest?
Correct Answer
A. Temperature: Cold; Light: Dim; Air: Damp
Explanation
Transpiration is the process by which water is lost from the leaves of a plant through evaporation. In cold temperatures, the rate of transpiration is slower because the water molecules evaporate more slowly. Dim light also reduces transpiration as it limits the energy available for evaporation. Damp air contains more moisture, which reduces the concentration gradient between the leaf and the surrounding air, thus slowing down transpiration. Therefore, under the conditions of cold temperature, dim light, and damp air, transpiration would be the slowest.
4.
The graph below shows the results of an
investigation in oxygen release and oxygen intake by a green plant in different
light conditions.
For how many hours did respiration and
photosynthesis take place during the investigation?
Correct Answer
C. Respiration (hours): 10; pHotosynthesis (hours): 7
Explanation
The correct answer indicates that respiration took place for 10 hours and photosynthesis took place for 7 hours during the investigation. This can be determined by looking at the values provided in the graph and matching them with the answer options.
5.
Mr. and Mrs. Lim are
married for 10 years and decided to start a family. During the consultation,
they have learnt that the probability of their first male child is 50%. Predict the probability of them having
a second child to be a male again.
Correct Answer
A. 25%
Explanation
The probability of having a male child is determined by the sex chromosomes carried by the parents. In this case, the probability of having a male child for Mr. and Mrs. Lim is 50%. However, the probability of having a male child for their second child is also 50%. Each child is an independent event, and the probability of having a male child does not change based on the gender of the previous child. Therefore, the probability of them having a second male child is also 50%.
6.
Country A has a high
percentage of population diagnosed with diabetes. As a result, there is a
sudden high demand for insulin in the health industry. Assuming you are a
leading medical consultant in the health industry, how would you propose to the
Health Minister an effective solution that will increase the insulin stock with
the minimum cost within the shortest time?
Correct Answer
C. Production of insulin by biofermentation
Explanation
Production of insulin by biofermentation is the most effective solution to increase insulin stock with minimum cost and shortest time. Biofermentation involves using microorganisms, such as bacteria or yeast, to produce insulin in large quantities. This method is highly efficient and cost-effective compared to other options like transplantation or isolation from farm animals. Additionally, biofermentation allows for scalability, meaning it can meet the sudden high demand for insulin in a short period of time. Stem cell therapy and transplantation are more complex and time-consuming processes that may not be feasible in the given scenario.
7.
Which description corresponds to a neutron?
Correct Answer
B. Mass = 1, electric charge = 0
Explanation
A neutron is a subatomic particle with a mass of 1 and an electric charge of 0. Unlike protons and electrons, which have electric charges of +1 and -1 respectively, neutrons are electrically neutral. They are found in the nucleus of an atom alongside protons and are responsible for adding to the mass of an atom without contributing to its overall charge.
8.
Which one of the following
reactions shows the formation of a compound from two elements?
Correct Answer
B. Magnesium + sulfur → magnesium sulfide
Explanation
The correct answer is "magnesium + sulfur → magnesium sulfide." This reaction shows the formation of a compound (magnesium sulfide) from two elements (magnesium and sulfur).
9.
A small amount of a dense white
powder was mixed with water in a test tube. None of the white powder sank to
the bottom of the test tube. A few drops of universal indicator were added
and the solution turned blue. What can you say about the nature of the white
powder?
Correct Answer
D. A very soluble alkali
Explanation
The white powder is classified as a very soluble alkali because when it was mixed with water, none of it sank to the bottom of the test tube. Additionally, when universal indicator was added, the solution turned blue, indicating that it has a high pH and is alkaline in nature.
10.
Which of the following graphs represents how
the temperature of gas varies as it eventually becomes a solid?
Correct Answer
C. 3
11.
Compound Q melts at 78 oC and
boils at 124 oC and is not soluble in water. Which apparatus can be
used to obtain pure Q from a mixture of Q and water.
Correct Answer
A. Apparatus A
Explanation
Apparatus A can be used to obtain pure compound Q from a mixture of Q and water because compound Q is not soluble in water. Apparatus A is likely a distillation apparatus, which can separate the mixture based on the difference in boiling points between compound Q and water. By heating the mixture, compound Q will vaporize and can be collected as a pure substance, while water will remain in the liquid phase.
12.
The chart below shows the
percentage of heat energy reflected by different materials A, B, C and D.
Which of the following combinations is the worst
suited for use exteriorly to cool a house in hot climates?
Correct Answer
D. Material D made of layers of soil
Explanation
The chart shows that material D, made of layers of soil, reflects the least amount of heat energy compared to the other materials. In hot climates, it is important to use materials that reflect heat to keep the house cool. Therefore, material D is the worst suited for use exteriorly to cool a house in hot climates.
13.
When a force is applied to a
body, several effects are possible.
Which of the following effects could not occur?
Correct Answer
D. The mass of the body decreases.
Explanation
When a force is applied to a body, several effects are possible. The body can change direction, slow down, or speed up. However, the mass of the body cannot decrease as a result of the force applied. The mass of an object is a fundamental property that remains constant unless there is a change in the amount of matter. Therefore, the correct answer is that the mass of the body cannot decrease.
14.
An iron ball of 10 kg sinks in
water with a uniform speed of 2 m/s.
Which of the following statements on the forces acting on the iron
ball is correct?
Correct Answer
A. The downward force is equal to the upward force.
Explanation
The correct answer is that the downward force is equal to the upward force. This is because the iron ball is sinking with a uniform speed, which means that the forces acting on it are balanced. The downward force is equal to the weight of the ball, which is equal to the upward buoyant force exerted by the water. Therefore, the two forces are equal in magnitude, resulting in a balanced situation where the ball sinks at a constant speed.
15.
A uniform beam is pivoted at its midpoint. An object is placed on the beam as
shown. Which force will re-balance
the system?
Correct Answer
C. 25 N acting downward, 20 cm to the right of the midpoint.
Explanation
The force that will re-balance the system is 25 N acting downward, 20 cm to the right of the midpoint. This force creates a clockwise torque, which counteracts the counterclockwise torque created by the object on the beam. The torques balance each other out, resulting in a stable equilibrium.
16.
The figure below shows how the position d of a toy
car changes with time t. Which of
the following statement best describes the motion of the toy car?
Correct Answer
B. The toy car’s highest speed is between 0 to 5 second.
Explanation
The correct answer is "The toy car’s highest speed is between 0 to 5 seconds." This can be determined by looking at the graph of the position-time relationship. Between 0 to 5 seconds, the slope of the graph is steeper, indicating a higher speed. After 5 seconds, the slope becomes less steep, indicating a decrease in speed. Therefore, the highest speed occurs between 0 to 5 seconds.
17.
The base area of four
different pairs of snowshoes are shown below. Which pair of snowshoes should Jack buy if he does not
want to sink into the snow while walking?
Correct Answer
D. 0.5 square meter
Explanation
Jack should buy the pair of snowshoes with the largest base area, which is 0.5 square meters. A larger base area will distribute his weight over a larger surface area, reducing the pressure exerted on the snow and preventing him from sinking into it while walking.
18.
Jeremy wants to study the
conversion of potential energy of a tennis ball to kinetic energy as it moves
down a ramp. Which of the
following apparatus is not needed to do the experiment?
Correct Answer
C. Spring balance
Explanation
A spring balance is not needed for this experiment because it is used to measure weight or force, which is not directly related to the conversion of potential energy to kinetic energy. The electronic balance is used to measure the mass of the tennis ball, the meter rule is used to measure the distance traveled by the ball, and the stopwatch is used to measure the time it takes for the ball to move down the ramp. These measurements are necessary to calculate the kinetic energy of the ball.