Biological Systems and Health
what is the small, circular loop of DNA is often found in bacterial cells and is frequently used in genetic engineering.
plasmids
Describe the arrangement and movement of particles in a solid.
Particles are packed closely together in a regular lattice and vibrate about fixed positions.
In the extraction of iron, what gas is the main reducing agent that removes oxygen from the iron ore in the Blast Furnace?
Carbon Monoxide (CO)
How is "acceleration" calculated using a speed-time graph?
By calculating the gradient (slope) of the line.
What is the formula for calculating Pressure?
Pressure = Force / area
Explain the functional advantage of a double circulatory system in mammals compared to the single circulatory system found in fish.
A double circulation maintains higher blood pressure to the body tissues, allowing for faster delivery of oxygen and glucose, which supports a higher metabolic rate and maintains body temperature.
Why do noble gases (Group VIII) exist as monoatomic gases and rarely form chemical bonds?
They have a full outer shell of electrons, making them stable and unreactive.
Identify which substance is being oxidized and which is being reduced in this reaction: Mg + CuO --> MgO + Cu.
Magnesium is oxidized (gains oxygen); Copper oxide is reduced (loses oxygen).
State the Law of Conservation of Energy.
Energy cannot be created or destroyed, only transferred from one form to another.
Why are the handles of cooking pans usually made of plastic or wood rather than metal?
Plastic and wood are thermal insulators, meaning they do not conduct heat well, keeping the handle cool.
When testing a food sample with Benedict’s solution, what color change indicates a high concentration of reducing sugars after heating?
From blue to brick-red.
Describe the arrangement of particles in this lattice and identify the two specific types of ions involved.
It is a regular, repeating arrangement (lattice) of alternating positive sodium ions Na+ and negative chloride ions Cl-.
Transition metals often act as catalysts. Explain how a catalyst increases the rate of a reaction without changing the temperature.
It provides an alternative reaction pathway with a lower activation energy, allowing more particles to have enough energy to react upon collision.
An object is dropped from a height. Describe the energy transfers taking place from the moment it is released until the moment just before it hits the ground (ignoring air resistance).
Gravitational Potential Energy is transferred into Kinetic Energy
Explain why a shiny, silver-colored surface is better than a dull, black surface for keeping a cold drink cool on a sunny day.
Shiny silver surfaces are poor absorbers (and good reflectors) of infrared radiation, so less heat is absorbed from the sun.
Describe the pathway of blood as it returns from the body to the lungs, naming the specific heart chamber it enters first and the vessel it leaves through.
superior/inferior vena cava, right atrium, right ventricle, pulmonary artery
Why does sodium chloride NaCl have a high melting point, whereas a simple covalent molecule like methane CH4 is a gas at room temperature?
NaCl has strong electrostatic forces between ions in a giant lattice that require a lot of energy to break; methane has weak intermolecular forces that are easily overcome.
Balance this equation:
___ Ca3(PO4)2 + ___ SiO2 + ___ C --> ___ CaSiO3 + ___ CO + ___ P
1,3,5 --> 3,5,2
A car of mass 1.2 x 106 grams accelerates at 2 m/s2. Calculate the resultant force required to achieve this.
2,400 N
Calculate the cost of using a 2.5 kW electric oven for 4 hours if the cost per unit (kWh) is $0.12.
$1.20 (2.5 x 4 = 10 kWh) (10 x 0.12)
Using the concept of concentration gradients, explain why a person with a high-sugar diet might experience a decrease in the rate of water absorption in the small intestine via osmosis.
If the concentration of solutes (sugar) in the lumen of the intestine is very high, it lowers the water potential gradient between the intestine and the blood. This means less water moves into the blood via osmosis, and in extreme cases, water could even be drawn out of the cells into the gut.
A gas is held in a cylinder with a movable piston. If the volume of the gas is halved while the temperature is kept constant, explain in terms of the Kinetic Particle Theory what happens to the frequency of collisions and the resulting pressure.
Halving the volume crowds the particles into a smaller space. Therefore, the frequency of collisions between the particles and the walls of the container increases. Since pressure is defined as force per unit area, the increased frequency of collisions results in a higher total force, thus doubling the pressure (Boyle’s Law).
In the extraction of iron from haematite, describe the chemical process that occurs to remove the main impurity, sand. Your answer must include the name of the compound added to remove it and the name of the product formed as well as all 3 balanced equations of the process.
carbon monoxide (3 molecules), pure iron
C + O2 → CO2
CO2 + C → 2CO
3CO + Fe2O3 → 2Fe + 3CO2
A student does 150 J of work to lift a 5kg box onto a shelf. If the gravitational field strength is 10 N/kg, calculate the height of the shelf and determine the power generated if the lift took 2 seconds.
Work = mgh
*remember formula for power*
3 meters
75 watts (power = w / t)
he Earth receives a vast amount of energy from the Sun, despite there being a vacuum in the space between them. Explain why conduction and convection are impossible methods for this energy transfer, and identify the specific part of the electromagnetic spectrum responsible for most of this thermal transfer. Finally, explain why a satellite in space is often wrapped in gold-colored "multi-layer insulation"
Conduction and convection both require particles (a medium) to transfer energy; since space is a vacuum, these cannot occur. The energy is transferred via Infrared Radiation. Satellites use gold-colored or reflective wrapping because these surfaces are poor absorbers of radiation, preventing the sun’s intense thermal energy from overheating the delicate electronic instruments inside.