Cellular Biology & Digestive Systems
Which cell structure acts as a massive internal reservoir for cell sap and maintains cellular volume?
central vacuole
In any standard ecosystem food web, what specific biological term is given to green plants, such as grass or corn, that generate their own organic nutrients via sunlight?
producers
What chemical term describes a pure substance consisting of molecules or atoms that contain only one specific type of atom?
an element
In practical laboratory chemistry, what is meant by the term "inert electrode," and what is a common material used to make one?
An inert electrode is an electrical conductor that permits current to enter and leave an electrolyte solution without undergoing any chemical reactions itself; it is commonly made of carbon (graphite) or platinum.
State the fundamental differences between an objects mass and weight and what would change if an object was moved to another planet with different gravity.
Mass is the amount of matter in an object and remains constant everywhere. Weight is the gravitational force acting on that mass and changes depending on the gravitational field strength of the planet.
What precise energy transformation occurs inside a plant's chlorophyll molecules during the process of photosynthesis?
light energy is converted into chemical energy
In a food web where Grass --> Grasshopper --> Lizard --> Snake --> Hawk, list every organism that is a secondary consumer and every organism that is a tertiary consumer.
The lizard is the secondary consumer, and the snake is the tertiary consumer.
For what specific reason is chlorine gas added during the final stages of municipal domestic water treatment?
To sterilize the water supply by killing harmful microbes and pathogens.
During the process of electrolysis, toward which specific electrode do positively charged ions (cations) always migrate?
Cathode
Draw or describe the standard electrical schematic symbol used to represent a light emitting diode (LED) in a circuit diagram
a triangle pointing against a vertical blocking line with two small arrows nearby pointing diagonally away to indicate light emission.
Identify the structural region of the human alimentary canal where the process of ingestion occurs, and name the distinct region where the primary absorption of nutrients into the bloodstream takes place.
Ingestion occurs in the mouth; the absorption of nutrients takes place in the small intestine.
Explain the scientific reasoning behind why the arrows in a food web diagram always point away from the organism being eaten and toward the organism consuming it.
represents teh flow of energy and organic biomass from one trophic level to another.
State the precise color change observed when water is added to anhydrous cobalt (II) chloride, and identify what this test detects.
The compound changes from blue to pink, which serves as a chemical test to confirm the presence of water.
List the chemical names or symbols of all four ions present simultaneously inside an aqueous solution of lead (II) bromide (PbBr2).
Pb2+, Br-, H+, OH-
Our Sun is currently a main sequence star. Name the two opposing physical forces that must remain perfectly balanced to maintain the sun's structural stability.
The inward pull of gravitational force (which acts to collapse the star) is balanced by the outward thermal radiation pressure generated by nuclear fusion reactions occurring in the core.
Glucose produced during photosynthesis is used to synthesize other complex plant and animal carbohydrates. Name two complex carbohydrates made from glucose monomers, and state their biological uses.
Starch (energy storage in plants), cellulose (structural component of plant cell walls), and glycogen (energy storage in animals).
Explain why food chains in natural ecosystems rarely contain more than four or five trophic levels, referencing the rule of energy transfer efficiency.
Energy is lost at each trophic level (roughly 90% is lost to respiration, movement, and heat), meaning only about 10% of the energy is passed to the next level. After four or five levels, there is not enough energy left to support another population.
You are given four sealed containers. Container A holds loose, unbonded atoms of Helium and Neon gas. Container B holds diatomic molecules of O2 and N2. Container C holds CO2 and H2O vapor. Container D holds methane (CH4) and O2. Classify each container as a mixture of elements, a mixture of compounds, or both.
Container A = mixture of elements
Container B = mixture of elements
Container C = mixture of compounds
Container D = both element and compound
Explain why a solid block of lead (II) bromide (PbBr2) acts as a total electrical insulator, whereas melting the substance allows it to conduct electricity and undergo electrolysis
In the solid state, the ions are locked into fixed positions within a rigid giant ionic lattice and cannot move to carry charge. When melted, the ionic lattice breaks down, allowing the ions to move freely toward the electrodes and conduct electricity.
Convert a journey duration of exactly 3.5 hours into seconds, and express your final value in standard scientific notation.
1.26 x 104 s
If a metabolic poison completely stops ATP production via respiration within a root hair cell, describe the immediate and long-term impacts on the absorption of nitrate ions and water molecules.
Nitrate ion uptake stops immediately because it relies on active transport, which requires ATP. Water absorption will slow down over time because without active accumulation of mineral ions, the cell cannot maintain the steep osmotic concentration gradient needed to drive passive water movement via osmosis.
Following the scenario where grass is entirely replaced by corn, predict the cascading secondary effects on hawks, which prey on both rabbits and corn-eating mice.
Hawks will experience an increased reliance on hunting mice due to the decline in rabbits. This intensified predation pressure may cause a secondary decline in the mouse population, potentially leading to food scarcity for the hawks later on.
Explain why ionic compounds like lithium fluoride (LiF) have exceptionally high melting points and conduct electricity when molten, whereas simple covalent molecules like ethene (C2H4) have very low boiling points and never conduct electricity
Lithium fluoride forms a giant ionic lattice held together by strong electrostatic forces between oppositely charged ions, which require significant thermal energy to overcome. These ions become free to move and carry a current only when melted. Ethene exists as simple covalent molecules held together by weak intermolecular forces that break easily at low temperatures, and it contains no free ions or delocalized electrons to conduct electricity
A student collects a sample of a clear, colorless liquid from a river during a science field trip. To analyze it using topics from the exam, they must complete two practical steps:
First, they want to chemically prove that the liquid actually contains water. Name the specific chemical indicator they should use, and state the exact color change they will see.
Second, even though the water looks clean, it contains dangerous, invisible bacteria. Name the substance that must be added to the water supply to kill these microbes and make it safe to drink.
They should use anhydrous cobalt (II) chloride, which will change color from blue to pink. 2. They must add chlorine (chlorine gas) to kill the microbes and pathogens.
A vehicle journey is plotted on a distance-time graph. From point P (t 0 os, d= 0m) to point Q (t = 10s, d =50m), the line curves upward with an increasing slope. From point Q to point R(t = 30s) d= 250m), the line is perfectly straight. Calculate the exact speed of the vehicle between points Q and R, and identify the type of motion occurring between points P and Q.
speed is 10 m/s (250-50)/(30-10). The motion is acceleration