GED Science Test #7 2 — Questions and Answers
Question 1: Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?
- Ribosome
- Mitochondria (Correct answer)
- Nucleus
- Golgi apparatus
Correct answer: Mitochondria
Mitochondria are called the powerhouse of the cell because they generate most of the cell's supply of ATP through the process of cellular respiration.
Mitochondria carry out cellular respiration, converting nutrients (primarily glucose) and oxygen into ATP, water, and carbon dioxide. This process occurs across the inner mitochondrial membrane via the electron transport chain, making mitochondria the primary ATP-producing organelles in eukaryotic cells.
Question 2: A car travels 150 miles in 3 hours and then 120 miles in 2 hours. What is the car's average speed for the entire trip?
- 50 mph
- 54 mph (Correct answer)
- 60 mph
- 270 mph
Correct answer: 54 mph
Average speed = total distance ÷ total time = (150 + 120) ÷ (3 + 2) = 270 ÷ 5 = 54 mph.
Average speed is calculated by dividing total distance by total time. Total distance = 150 + 120 = 270 miles. Total time = 3 + 2 = 5 hours. Average speed = 270 ÷ 5 = 54 mph. Note: average speed is not simply the average of the two individual speeds (50 mph and 60 mph), because different amounts of time were spent at each speed.
Question 3: Which of the following best describes the role of decomposers in an ecosystem?
- They convert sunlight into chemical energy
- They break down dead organic matter and recycle nutrients (Correct answer)
- They consume living plants for energy
- They fix nitrogen from the atmosphere
Correct answer: They break down dead organic matter and recycle nutrients
Decomposers such as bacteria and fungi break down dead organisms and organic waste, returning nutrients like nitrogen and carbon back into the soil and atmosphere for reuse by producers.
Decomposers (mainly bacteria and fungi) are critical to nutrient cycling. They break down complex organic molecules in dead organisms and waste into simpler inorganic compounds. These nutrients are then released into the soil and water, where they can be taken up again by plants and other producers, completing biogeochemical cycles like the carbon and nitrogen cycles.
Question 4: Earth's layers from outermost to innermost are:
- Crust, mantle, outer core, inner core (Correct answer)
- Mantle, crust, outer core, inner core
- Crust, outer core, mantle, inner core
- Inner core, outer core, mantle, crust
Correct answer: Crust, mantle, outer core, inner core
Earth is structured in concentric layers: the thin solid crust on the outside, followed by the thick mantle, then the liquid outer core, and finally the solid inner core at the center.
Earth's four main layers are arranged by density and composition. The crust is the thinnest, outermost solid layer. Beneath it is the mantle, the thickest layer, composed of semi-solid rock. The outer core is liquid iron and nickel, and its movement generates Earth's magnetic field. The inner core is a solid ball of iron and nickel at extremely high pressure and temperature.
Question 5: Which type of chemical bond involves the sharing of electron pairs between atoms?
- Ionic bond
- Metallic bond
- Covalent bond (Correct answer)
- Hydrogen bond
Correct answer: Covalent bond
A covalent bond is formed when two atoms share one or more pairs of electrons. This type of bonding is common in molecules like water (H₂O) and carbon dioxide (CO₂).
In a covalent bond, atoms share electron pairs to achieve a stable electron configuration. This differs from ionic bonds, where electrons are transferred from one atom to another. Covalent bonds are strong and directional, forming distinct molecules. Examples include the O-H bonds in water and the C=O bonds in carbon dioxide.
Question 6: According to the graph showing population growth, which growth pattern results in a J-shaped curve?
- Logistic growth
- Exponential growth (Correct answer)
- Linear growth
- Seasonal growth
Correct answer: Exponential growth
Exponential growth produces a J-shaped curve because the population grows at a rate proportional to its current size — the larger the population, the faster it grows — with no limiting factors slowing it down.
Exponential growth occurs when a population's growth rate remains constant, causing the population to double repeatedly in equal time intervals. This creates a J-shaped curve on a graph. In contrast, logistic growth produces an S-shaped (sigmoidal) curve because growth slows as the population approaches the carrying capacity of its environment, where resources become limiting factors.
GED Science Test #7 2
Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?