A Living organisms
B Preserved remains of ancient organisms
C Genetic mutations
D Embryonic structures
Explanation: Fossils are preserved remains or traces of organisms from past geological ages.
A Plantae
B Animalia
C Fungi
D Protista
Explanation: Fungi are heterotrophic organisms that absorb nutrients, including mushrooms, yeasts, and molds.
A Grass
B Lion
C Mushroom
D Eagle
Explanation: Mushrooms are fungi that break down dead organic matter, recycling nutrients back into the ecosystem.
A Food web
B Energy pyramid
C Biogeochemical cycle
D Ecological succession
Explanation: Energy pyramids show the decrease in available energy at each trophic level.
A Competition
B Predation
C Natural disaster
D Disease
Explanation: Natural disasters affect populations regardless of their density.
A Oxygen
B Nitrogen
C Carbon dioxide
D Hydrogen
Explanation: CO2 traps heat in the atmosphere, preventing infrared radiation from escaping to space.
A Bacteria
B Temperature
C Trees
D Insects
Explanation: Temperature is a non-living (abiotic) component of an ecosystem.
A Tundra
B Desert
C Tropical rainforest
D Grassland
Explanation: Tropical rainforests have the highest species diversity due to warm temperatures and abundant rainfall.
A Primary consumer
B Secondary consumer
C Tertiary consumer
D Decomposer
Explanation: Primary consumers (herbivores) feed directly on producers (plants).
A Number of genes in a species
B Variety of life in a given area
C Number of cells in an organism
D Rate of evolution
Explanation: Biodiversity is the variety of all living organisms including species, genetic, and ecosystem diversity.
A Cell -> Organ -> Tissue -> Organ system
B Cell -> Tissue -> Organ -> Organ system
C Tissue -> Cell -> Organ -> Organ system
D Organ -> Tissue -> Cell -> Organ system
Explanation: Biological organization progresses from cells to tissues to organs to organ systems.
A Lipids
B Carbohydrates
C Proteins
D Nucleic acids
Explanation: Enzymes are proteins that speed up biochemical reactions without being consumed.
A Non-competitive inhibition
B Competitive inhibition
C Irreversible inhibition
D Allosteric inhibition
Explanation: Competitive inhibitors compete with the substrate for binding at the enzyme\'s active site.
Explanation: Human blood pH is tightly regulated between 7.35 and 7.45 by buffer systems.
A Sucrose
B Maltose
C Fructose
D Lactose
Explanation: Fructose is a monosaccharide, a simple sugar that cannot be hydrolyzed further.
A Organic solvents
B Chloroform
C Water
D Benzene
Explanation: Lipids are hydrophobic molecules that are insoluble in water but soluble in organic solvents.
A Glycosidic bond
B Peptide bond
C Phosphodiester bond
D Hydrogen bond
Explanation: Peptide bonds form between the amino group of one amino acid and the carboxyl group of another.
A Adenosine triphosphate
B Adenosine diphosphate
C Adenine triphosphate
D Amino triphosphate
Explanation: ATP (Adenosine triphosphate) is the primary energy currency of the cell.
A They are consumed in reactions
B They increase activation energy
C They are specific to substrates
D They work at all temperatures
Explanation: Enzymes are substrate-specific due to the complementary shape of their active site.
A Mitochondria
B Nucleus
C Cytoplasm
D Endoplasmic reticulum
Explanation: Glycolysis takes place in the cytoplasm, breaking glucose into two molecules of pyruvate.