Ecology
A farmer sprays pesticides to eliminate insects. Several weeks later, the insect population decreases, and the frog population also declines. Which explanation best describes how the pesticide could affect the ecosystem?
A. Frogs may consume contaminated insects, causing toxins to move through the food web.
B.Pesticides increase the amount of energy available to frogs.
C.Frogs stop reproducing because plants no longer perform photosynthesis.
D.The pesticide directly increases the carrying capacity of the ecosystem.
A. Frogs may consume contaminated insects, causing toxins to move through the food web.
A cell's mitochondria stop functioning properly. Which combination of effects is most likely?
A. ATP production decreases, disrupting active transport and other energy-requiring processes.
B. DNA replication increases, causing the cell to divide faster.
C. The cell membrane becomes completely impermeable to water.
D. Ribosomes begin producing energy instead of proteins.
A. ATP production decreases, disrupting active transport and other energy-requiring processes.
Two heterozygous tall pea plants (Tt) are crossed. Tall (T) is dominant over short (t). Which prediction is correct?
A. 100% tall offspring
B. 25% tall and 75% short offspring
C.50% tall and 50% short offspring
D. 75% tall and 25% short offspring
D. 75% tall and 25% short offspring
A population of insects contains green and brown individuals. The environment becomes covered in brown leaves, and brown insects become more common. Which explanation best describes this change?
A. Brown insects intentionally change their color to survive.
B. Green insects stop inheriting their traits.
C. Brown insects have a camouflage advantage and reproduce more successfully.
D. The environment causes all insects to develop identical mutations.
C. Brown insects have a camouflage advantage and reproduce more successfully.
A scientist observes that bacteria and animal cells both contain DNA and ribosomes. However, only animal cells contain a nucleus and membrane-bound organelles. Which conclusion is best supported?
A. Both are prokaryotic cells.
B. Animal cells lack genetic information.
C. Bacteria are prokaryotic, while animal cells are eukaryotic.
D. Bacteria contain more membrane-bound organelles than animal cells.
C. Bacteria are prokaryotic, while animal cells are eukaryotic.
A grassland ecosystem contains grass, grasshoppers, mice, snakes, and hawks. If grass contains 20,000 units of energy, approximately how much energy would be available to hawks through a grasshopper → snake → hawk pathway?
A. 2,000 units
B.200 units
C. 20 units
D. 2 units
D. 2 units
A pancreatic cell produces insulin, a protein hormone. If the Golgi apparatus stops functioning, which process would most likely be disrupted?
A. DNA replication in the nucleus
B. The movement of water through the membrane
C. The formation of ATP in mitochondria
D. Modification, packaging, and secretion of insulin
D. Modification, packaging, and secretion of insulin
A scientist identifies a DNA mutation in a gene. Which explanation best describes how this mutation could affect protein production?
A. It may change an mRNA codon and alter the amino acid sequence of a protein.
B. It always prevents DNA from being copied.
C. It automatically changes every chromosome in the cell.
D. It always causes the cell to produce additional proteins.
A. It may change an mRNA codon and alter the amino acid sequence of a protein.
A population of bacteria is exposed to an antibiotic. Most bacteria die, but a few resistant bacteria survive and reproduce. Which statement best explains the outcome?
A. The antibiotic causes every bacterium to develop resistance because it needs to survive.
B. Resistant bacteria already had genetic variations that allowed them to survive and reproduce.
C. Bacteria choose to become resistant when exposed to antibiotics.
D. The antibiotic increases the mutation rate in every surviving bacterium in a predictable way.
B. Resistant bacteria already had genetic variations that allowed them to survive and reproduce.
A virus enters a human cell and uses the host's ribosomes to make viral proteins. What does this observation demonstrate?
A. Viruses have their own complete protein synthesis machinery.
B. Viruses perform photosynthesis inside host cells.
C. Viruses are made of cells that contain nuclei.
D. Viruses depend on host-cell machinery to reproduce.
D. Viruses depend on host-cell machinery to reproduce.
A deer population increases rapidly after predators are removed. Several years later, the population declines because food and water become limited. Which prediction is best if predators are reintroduced?
A. The deer population will increase indefinitely.
B.Predation may reduce the deer population and help restore balance with available resources.
C. The carrying capacity will automatically double.
D.The deer will stop competing for resources.
B. Predation may reduce the deer population and help restore balance with available resources.
A plant is placed in complete darkness but continues receiving water and carbon dioxide. Which prediction best explains what happens?
A. Photosynthesis continues at the same rate because water is available.
B. Cellular respiration stops immediately because light is absent.
C. Photosynthesis decreases, but cellular respiration can temporarily use stored glucose.
D. The plant produces additional glucose without light.
C. Photosynthesis decreases, but cellular respiration can temporarily use stored glucose.
Two biological siblings have different combinations of inherited traits. Which processes best explain this variation?
A. Binary fission and mitosis
B. Diffusion and osmosis
C. Crossing over and independent assortment during meiosis
D. DNA replication without chromosome separation
C. Crossing over and independent assortment during meiosis
Scientists discover fossils of extinct organisms that share anatomical similarities with modern organisms. Which conclusion is best supported by this evidence?
A. Fossils and homologous structures provide evidence that organisms may share common ancestors.
B. All modern organisms evolved directly from the same living species.
C. Similar structures prove that two organisms are the same species.
D. Fossils cannot provide evidence of evolutionary change.
A. Fossils and homologous structures provide evidence that organisms may share common ancestors.
Mitochondria and chloroplasts contain their own DNA and have structures resembling certain bacteria. Which theory is best supported by these observations?
A. Endosymbiotic theory
B. Cell Theory
C. Natural selection theory
D.Germ theory
A. Endosymbiotic theory
A forest experiences a major decrease in its decomposer population. Which long-term consequence is most likely?
A. Nutrients will be recycled faster, increasing plant growth.
B. Organic matter will accumulate, and nutrient availability for producers may decrease.
C. Photosynthesis will stop immediately in all plants.
D.Consumers will receive more energy from decomposers.
B. Organic matter will accumulate, and nutrient availability for producers may decrease.
Three identical plant cells are placed in hypotonic, isotonic, and hypertonic solutions. Which statement correctly compares the cells?
A. Water leaves all three cells at the same rate.
B. Water movement occurs only in the isotonic cell.
C. Water leaves the hypotonic cell and enters the hypertonic cell.
D. Water enters the hypotonic cell, has no net movement in the isotonic cell, and leaves the hypertonic cell.
B. Water enters the hypotonic cell, has no net movement in the isotonic cell, and leaves the hypertonic cell.
Two parents do not show a recessive genetic disorder, but they have an affected child. What is the probability that their next child will also have the disorder?
A. 0%
B. 25%
C. 50%
D. 100%
B. 25%
A hurricane randomly kills 80% of a small island population of lizards. The surviving population has different allele frequencies. Which mechanism best explains this change?
A. Natural selection
B. Gene flow
C. Genetic drift through the bottleneck effect
D. Artificial selection
C. Genetic drift through the bottleneck effect
A rabbit population changes over four generations. Brown-fur rabbits increase from 40 to 90, while white-fur rabbits decrease from 60 to 10. The environment contains increasing amounts of brown vegetation. Which explanation best accounts for the data?
A. Brown rabbits likely had greater camouflage, increasing their survival and reproduction.
B. White rabbits intentionally changed their fur color to brown.
C. The population experienced no evolutionary change.
D. Brown fur became more common because all rabbits developed the same mutation at the same time.
A. Brown rabbits likely had greater camouflage, increasing their survival and reproduction.
A lake receives excessive fertilizer runoff. An algal bloom develops, followed by low dissolved oxygen and fish deaths. Which sequence best explains the fish die-off?
A. Fertilizer increases algae, algae die, decomposers break them down and consume oxygen, and fish suffocate.
B. Fertilizer decreases algae, which causes fish to lose their food source immediately.
C. Algae release excess oxygen, causing fish cells to lose homeostasis.
D. Fertilizer directly increases the lake's carrying capacity for fish.
A. Fertilizer increases algae, algae die, decomposers break them down and consume oxygen, and fish suffocate.
A single-celled alga contains chloroplasts and mitochondria. During daylight, it produces more oxygen than it consumes. At night, it consumes oxygen and releases carbon dioxide. Which explanation best accounts for these observations?
A. Photosynthesis occurs during both day and night, but respiration occurs only at night.
B. During daylight, photosynthesis produces oxygen faster than respiration consumes it; at night, respiration continues without photosynthesis.
C. Mitochondria produce glucose during the day and chloroplasts release carbon dioxide at night.
D. The organism stops all cellular processes at night.
B. During daylight, photosynthesis produces oxygen faster than respiration consumes it; at night, respiration continues without photosynthesis.
A single nucleotide is inserted near the beginning of a gene. Why could this mutation have a greater effect on the resulting protein than a substitution mutation?
A. An insertion can shift the reading frame, changing multiple codons and amino acids.
B. A substitution always removes an entire chromosome.
C. An insertion prevents all RNA from entering the nucleus.
D. A substitution always causes a frameshift.
A. An insertion can shift the reading frame, changing multiple codons and amino acids.
A mountain range separates one bird population into two groups. Over many generations, the groups develop different mating behaviors and genetic characteristics. Which condition would provide the strongest evidence that speciation has occurred?
A.
Both groups continue mating and producing fertile offspring.
B. The two groups move back together and exchange alleles regularly.
C. Both groups develop identical beak shapes.
D. The groups develop reproductive isolation and can no longer successfully interbreed to produce fertile offspring.
D. The groups develop reproductive isolation and can no longer successfully interbreed to produce fertile offspring.
During a drought, plants with deeper roots survive more often and produce more seeds than plants with shallow roots. Which explanation best connects genetics and evolution?
A. Individual plants develop deeper roots because they need them, and pass the acquired change to offspring.
B. Inherited genetic variation in root depth allows some plants to survive and reproduce more, increasing beneficial alleles over generations.
C. All plants experience identical reproductive success regardless of inherited traits.
D. Drought conditions prevent natural selection from occurring.
B. Inherited genetic variation in root depth allows some plants to survive and reproduce more, increasing beneficial alleles over generations.