CTJan27 Online JMSS - Science Resoning 10042026

A simplified food web for a grassland ecosystem is described as follows:

• Grass is eaten by grasshoppers and mice.
• Grasshoppers are eaten by mice and hawks.
• Mice are eaten by snakes and hawks.
• Snakes are eaten by hawks.

If the population of snakes suddenly and significantly decreased due to a disease, which of the following populations would most likely be the first to increase?

A student conducted an experiment to determine which colour of light is most effective for plant growth. Four identical plants were grown for one month under different coloured lights, with all other conditions (water, soil, temperature) kept constant. The final average height of the plants was recorded and is shown in the bar chart below.

Based on the data presented in the chart, which conclusion is best supported?

A student designed an experiment to investigate how temperature affects the rate of a reaction between magnesium ribbon and hydrochloric acid. The plan is as follows:

1. Set up three beakers with hydrochloric acid at $10^{\circ}$C, $20^{\circ}$C, and $30^{\circ}$C.
2. Add a 5 cm piece of magnesium ribbon to the first beaker ($10^{\circ}$C) and time how long it takes for the magnesium to disappear.
3. Add a 10 cm piece of magnesium ribbon to the second beaker ($20^{\circ}$C) and time how long it takes for the magnesium to disappear.
4. Add a 15 cm piece of magnesium ribbon to the third beaker ($30^{\circ}$C) and time how long it takes for the magnesium to disappear.

What is the most significant flaw in this experimental design?

The graph below shows the heating curve for a pure substance, starting from a solid state. Heat is added at a constant rate.

The distance-time graph below represents the journey of a cyclist.

The graph has three segments:

• 0 to 10 seconds: A straight line from (0, 0) to (10, 50).
• 10 to 20 seconds: A horizontal line from (10, 50) to (20, 50).
• 20 to 30 seconds: A straight line from (20, 50) to (30, 0).

What was the cyclist doing between 10 and 20 seconds?

Consider the electrical circuit diagram shown below.

The circuit contains a battery, two switches (S1 and S2), and two identical bulbs (B1 and B2). Switch S1 is in the main part of the circuit. The circuit then splits into two parallel branches. Bulb B1 is in one branch. Bulb B2 and switch S2 are in the other branch.

If switch S1 is closed and switch S2 is left open, what will be the outcome?

The table below contains data for four planets in our Solar System.

Based on the data in the table, which relationship can be identified?

A scientist is conducting an investigation to determine if the pH of soil affects the colour of hydrangea flowers. The scientist plants five identical hydrangea cuttings in five separate pots with soil of varying pH levels (pH 5.0, 5.5, 6.0, 6.5, 7.0). All plants are given the same amount of water, sunlight, and fertiliser. After several weeks, the colour of the flowers on each plant is observed and recorded.

In this biological investigation, what is the independent variable?

In a simple ecosystem, grass is eaten by grasshoppers, grasshoppers are eaten by frogs, frogs are eaten by snakes, and snakes are eaten by hawks. If a disease eliminates the entire snake population, what is the most likely immediate consequence for the other populations?

A student conducted an experiment to see how different colours of light affect the average height of pea plants. All plants were given the same amount of water, soil, and were kept at the same temperature. The results after 3 weeks are shown below:

Which conclusion is best supported by the data?

A student wants to investigate the effect of temperature on the rate of reaction between a 5 cm strip of magnesium and hydrochloric acid. They set up three experiments:

• Setup 1: 50 mL of 1 M HCl at 20°C
• Setup 2: 50 mL of 2 M HCl at 30°C
• Setup 3: 50 mL of 1 M HCl at 40°C

They plan to compare the time taken for the magnesium to disappear in all three setups. Which statement best evaluates this experimental design?

The graph below shows the heating curve for an unknown substance as it is heated at a constant rate. What is the boiling point of the substance?

The distance-time graph below represents the journey of a cyclist. During which time interval is the cyclist moving with the fastest constant speed?

Consider a simple series circuit containing a battery and two identical light bulbs, L1 and L2. Both bulbs are glowing. If a wire is then connected in parallel across bulb L2, what will be the observed outcome?

A student investigates whether the concentration of fertiliser affects the growth of tomato plants. She plants three identical seedlings in identical pots with the same type of soil. She gives each plant the same amount of water and sunlight each day.

• Plant A receives no fertiliser.
• Plant B receives 5g of fertiliser per week.
• Plant C receives 10g of fertiliser per week.

She measures the height of the plants after four weeks. What is the independent variable in this investigation?

A research study finds that people who drink at least one cup of coffee per day have a 10% lower incidence of a certain disease than people who do not drink coffee. A news headline reads: "Coffee Cures Disease!" Why is this conclusion not valid based on the study?

In humans, brown eyes (B) are dominant to blue eyes (b). The pedigree chart below shows a family's eye colour. Shaded symbols represent individuals with blue eyes. What is the genotype of individual II-1?

• Generation I: A brown-eyed male (I-1) and a brown-eyed female (I-2)
• Generation II: They have three children: a brown-eyed male (II-1), a brown-eyed female (II-2), and a blue-eyed male (II-3).

A student is given a mixture containing water, fine sand (insoluble), and dissolved sugar. They need to separate the mixture to obtain pure solid sugar. Which sequence of separation techniques is the most appropriate?

An experiment was conducted to test the effectiveness of different materials for insulating a hot drink. Four identical cups were filled with 200 mL of water at 80°C. Each cup was wrapped with a different insulating material. The temperature was measured again after 10 minutes. The results are shown in the table.

Which material was the most effective insulator?

A species of rodent lives in a sandy, light-coloured desert environment. Most of the rodents have light-coloured fur, but a rare mutation results in dark-coloured fur. A new predator, which hunts by sight, is introduced into the area. Which hypothesis is most likely to be correct regarding the rodent population after many generations?

The climatograph below shows the average monthly temperature and precipitation for a particular city. Based on the data, what can be inferred about the city's location and climate?

A simple terrestrial food web consists of the following relationships: Grass is eaten by rabbits and grasshoppers. Rabbits are eaten by foxes. Grasshoppers are eaten by frogs, and frogs are eaten by snakes. What would be the most likely immediate effect if a disease eliminated most of the rabbit population?

A student wants to investigate how temperature affects the rate of reaction between magnesium ribbon and hydrochloric acid. They set up three beakers with acid at $10^\circ C$, $25^\circ C$, and $40^\circ C$. They add a 5 cm strip of magnesium to the first beaker, a 7 cm strip to the second, and a 6 cm strip to the third. They time how long it takes for the magnesium to disappear. What is the most significant flaw in this experimental design?

A pure substance, initially solid, is heated at a constant rate. Its temperature is recorded over time. The data shows the temperature increases steadily from $-10^\circ C$ to $0^\circ C$. It then remains at $0^\circ C$ for several minutes. After this, the temperature rises steadily again to $100^\circ C$, where it stays constant as the substance turns into a gas. Based on this information, what is the melting point of the substance?

The table below contains data for four fictional exoplanets orbiting a star similar to our Sun.

Which statement describes a relationship shown in the data?

An experiment is set up to investigate if the amount of light affects the rate of photosynthesis in pondweed. The rate is measured by counting the number of oxygen bubbles produced per minute. A lamp is placed at different distances (10 cm, 20 cm, 30 cm) from a beaker containing the pondweed. The temperature of the water and the concentration of carbon dioxide are kept the same for all trials. In this investigation, what is the dependent variable?

A study records the population of a native bird species and the population of a newly introduced insect species in a particular forest over five years.

A student concludes: "The increase in the bird population caused the decrease in the insect population because the birds eat the insects." Which statement best assesses this conclusion?

To test the effectiveness of different insulating materials, a student fills four identical cups with 200 mL of water at an initial temperature of $80^\circ C$. Each cup is wrapped with a different material of the same thickness. The temperature of the water in each cup is measured after 20 minutes.

Based on the data, which material is the most effective insulator?

A biologist hypothesises that the primary evolutionary advantage of a giraffe's long neck is to allow it to spot predators from a greater distance on the open savanna. Which of the following observations would provide the strongest evidence against this hypothesis?

A climatograph for an unknown location shows that the average monthly temperature is consistently high, varying only between $25^\circ C$ and $28^\circ C$ throughout the year. The precipitation data shows extremely high rainfall from May to October, and very low rainfall from November to April. Which type of environment is most likely represented by this climatograph?

A marine food web includes phytoplankton (producers), krill (eat phytoplankton), small fish (eat phytoplankton), squid (eat krill and small fish), seals (eat small fish and squid), and killer whales (eat seals). If ocean currents bring a massive upwelling of nutrients, causing a huge, sustained bloom in the phytoplankton population, which sequence of events is most likely to occur over the following months and years?

The table shows the results of an experiment on the effect of soil pH on the average mass of beans produced per plant.

Which is the most reasonable conclusion that can be drawn from these results?

A student hypothesises that a greater surface area of a solid reactant will increase the reaction rate. They test this by reacting 5g of marble chips (calcium carbonate) with 100 mL of hydrochloric acid in an open flask. They conduct trials with a single 5g chip, medium 5g chips, and 5g of powder. They measure the rate by placing the flask on a digital balance and recording the mass every 30 seconds. Why is measuring the change in mass an effective way to determine the reaction rate in this specific reaction ($CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$)?

A heating curve for a pure substance, heated at a constant rate, shows two plateaus. The first plateau (melting) occurs at $80^\circ C$ and lasts for 4 minutes. The second plateau (boiling) occurs at $150^\circ C$ and lasts for 8 minutes. What can be inferred from the fact that the second plateau is twice as long as the first?

The table shows data for four of Jupiter's moons. An astronomer proposes that moons that formed further from Jupiter are less dense because they incorporated more low-density ice during their formation.

Which piece of data most strongly suggests that the relationship between orbital distance and density is not a simple linear one?