GED Science 2 — Questions and Answers
Question 1: Which organelle is responsible for producing energy (ATP) in a eukaryotic cell?
- Nucleus
- Ribosome
- Mitochondria (Correct answer)
- Golgi apparatus
Correct answer: Mitochondria
Mitochondria are the 'powerhouses of the cell,' producing ATP through cellular respiration using oxygen and glucose.
Mitochondria are double-membraned organelles that produce adenosine triphosphate (ATP) through a process called cellular respiration. This process converts glucose and oxygen into ATP, carbon dioxide, and water. The inner membrane of the mitochondria is folded into structures called cristae, which greatly increase the surface area available for ATP production. Other organelle functions: • Nucleus: contains DNA, controls cell activities • Ribosomes: synthesize proteins • Golgi apparatus: packages and ships proteins • Endoplasmic reticulum: processes and transports proteins and lipids An interesting fact: mitochondria have their own DNA, leading scientists to believe they were once free-living bacteria that were incorporated into eukaryotic cells (endosymbiotic theory).
Question 2: Which process do plants use to convert light energy into chemical energy (food)?
- Cellular respiration
- Fermentation
- Photosynthesis (Correct answer)
- Transpiration
Correct answer: Photosynthesis
Photosynthesis is the process plants use to capture light energy and convert it into glucose (chemical energy), releasing oxygen as a byproduct.
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. The simplified equation is: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ (glucose) + 6O₂ This process occurs in chloroplasts, specifically in the green pigment chlorophyll, which absorbs primarily red and blue light (reflecting green, which is why plants appear green). Two stages of photosynthesis: 1. Light-dependent reactions (in the thylakoid membrane): capture light energy, produce ATP and NADPH 2. Calvin cycle / light-independent reactions (in the stroma): use ATP and NADPH to convert CO₂ into glucose Photosynthesis and cellular respiration are complementary: photosynthesis stores energy (produces glucose), while respiration releases it (breaks down glucose).
Question 3: What is the correct order of levels of biological organization from smallest to largest?
- Cell → Tissue → Organ → Organ system → Organism (Correct answer)
- Tissue → Cell → Organ → Organism → Organ system
- Organ → Cell → Tissue → Organism → Organ system
- Cell → Organ → Tissue → Organ system → Organism
Correct answer: Cell → Tissue → Organ → Organ system → Organism
Biological organization from smallest to largest: Cell → Tissue → Organ → Organ system → Organism.
The hierarchy of biological organization reflects increasing complexity: Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ system → Organism → Population → Community → Ecosystem → Biosphere For the GED, focus on the cellular levels: • Cell: the basic unit of life (e.g., muscle cell) • Tissue: a group of similar cells working together (e.g., muscle tissue) • Organ: a group of tissues working together (e.g., heart) • Organ system: organs working together for a function (e.g., circulatory system) • Organism: a complete living thing (e.g., a human) Example: Individual cardiac muscle cells → cardiac muscle tissue → heart (organ) → cardiovascular system → human being.
Question 4: In a food chain, which organism is the PRIMARY producer?
- Hawk
- Rabbit
- Grass (Correct answer)
- Fox
Correct answer: Grass
Producers (like grass) make their own food through photosynthesis. They form the base of food chains and are called autotrophs.
In an ecosystem's food chain, organisms are classified by how they obtain energy: • Producers (autotrophs): Make their own food through photosynthesis or chemosynthesis. Examples: grass, trees, algae, phytoplankton. They form the base of all food chains. • Primary consumers (herbivores): Eat producers. Examples: rabbits, deer, caterpillars. • Secondary consumers (carnivores or omnivores): Eat primary consumers. Examples: foxes, frogs. • Tertiary consumers: Eat secondary consumers. Examples: hawks, sharks. Energy flow: At each level, about 90% of energy is lost as heat, meaning only 10% transfers to the next level. This is why food chains rarely have more than 4-5 levels — there's not enough energy to support more. A hawk eating a rabbit that ate grass represents a 3-level food chain: grass → rabbit → hawk.
Question 5: Which of the following best describes the function of DNA in cells?
- Provides energy for cellular processes
- Carries oxygen through the bloodstream
- Contains genetic instructions for building proteins (Correct answer)
- Protects the cell from foreign invaders
Correct answer: Contains genetic instructions for building proteins
DNA (deoxyribonucleic acid) stores genetic information in the form of base sequences that code for proteins, which carry out most cellular functions.
DNA (deoxyribonucleic acid) is the molecule that carries genetic information in all living organisms. It serves as the instruction manual for the cell. DNA's key functions: 1. Stores genetic information: sequences of four bases (adenine, thymine, guanine, cytosine) encode instructions for building proteins 2. Replication: DNA can copy itself so genetic information passes to daughter cells during cell division 3. Gene expression: DNA sequences are transcribed into RNA, which is then translated into proteins The 'central dogma' of molecular biology: DNA → RNA → Protein Proteins built from DNA instructions perform nearly every function in the body: enzymes catalyze reactions, structural proteins form body tissues, antibodies fight infection, and hormones regulate body processes. Humans have about 3 billion base pairs of DNA packed into 46 chromosomes in nearly every cell.
Question 6: Which type of reproduction produces offspring that are genetically identical to the parent?
- Sexual reproduction
- Asexual reproduction (Correct answer)
- Cross-pollination
- Fertilization
Correct answer: Asexual reproduction
Asexual reproduction involves one parent and produces genetically identical offspring (clones) through processes like budding, fission, or vegetative propagation.
Asexual reproduction involves a single organism producing offspring without the fusion of gametes. The offspring are genetically identical to the parent (clones). Types of asexual reproduction: • Binary fission: bacteria split into two equal halves • Budding: new organism grows from the parent (e.g., yeast, hydra) • Vegetative propagation: plant parts grow into new plants (e.g., strawberry runners) • Fragmentation: organism breaks apart, each piece regenerates (e.g., starfish) • Parthenogenesis: egg develops without fertilization (e.g., some reptiles, bees) Sexual reproduction involves two parents contributing genetic material through gametes (sperm + egg), producing offspring with unique genetic combinations. This genetic variation is an evolutionary advantage in changing environments. Asexual reproduction advantage: faster, no need for a mate, works well in stable environments.
GED Science 2
Which organelle is responsible for producing energy (ATP) in a eukaryotic cell?