Q2 GEN BIO 2 (Mrs. Arenas)

Question 1

In a population, a gene for flower color has two alleles: one for red flowers (R) and one for white flowers (r). If a plant has the genotype Rr, what color will its flowers be, assuming R is dominant?

Answer 1

Red

The flowers will be red because the red allele (R) is dominant over the white allele (r). Even though the plant is heterozygous (Rr), the dominant allele will be expressed in the phenotype.

Question 2

A mother has brown eyes (Bb) and a father has blue eyes (bb). What are the possible genotypes and phenotypes of their children?

Answer 2

The possible genotypes of their children are Bb and bb.

• Bb: Brown eyes (dominant allele B is expressed).
• bb: Blue eyes (two recessive alleles are present). The phenotypes will be 50% brown eyes and 50% blue eyes.

Question 3

Two plants with yellow seeds (Yy) are crossed. What are the possible genotypes and phenotypes of their offspring?

Answer 3

The possible genotypes are YY, Yy, and yy.

YY and Yy: Yellow seeds (dominant allele Y is expressed).

yy: Green seeds (two recessive alleles are present).
The phenotypes will be 75% yellow seeds and 25% green seeds.

Question 4

During gamete formation, a parent with the genotype Aa produces sperm or egg cells. What alleles will the gametes carry?

Answer 4

The gametes will carry either the A allele or the a allele, but not both.

This is due to the Law of Segregation, which states that alleles separate during gamete formation.

Question 5

A plant has the genotype AaBb for two different genes. How many different combinations of alleles can its gametes have?

Answer 5

The gametes can have four different combinations of alleles: AB, Ab, aB, and ab.

This is due to the Law of Independent Assortment, which states that alleles for different genes segregate independently during gamete formation.

Question 6

A population of birds on an island has mostly red feathers. A few birds with blue feathers migrate to the island from the mainland. What is this called?

Answer 6

Gene Flow

The introduction of blue-feathered birds increases genetic variation in the island population by adding a new allele for feather color. Over time, gene flow may lead to a higher frequency of the blue allele if it provides a survival or reproductive advantage.

Question 7

A small population of frogs experiences a sudden drop in numbers due to a disease, leaving only a few individuals. What genetic phenomenon explains this change in allele frequency?

Answer 7

Genetic Drift

The genetic diversity of the population will likely decrease due to the bottleneck effect. The surviving individuals may not represent the full genetic variation of the original population, leading to a loss of alleles.

Question 8

A small group of squirrels with a rare allele for striped tails colonizes a new forest. How might the allele frequency in the new population compare to the original population?

Answer 8

The allele for striped tails may be more common in the new population due to the founder effect.

When a small group of individuals colonizes a new area, the resulting population will have a limited
gene pool, reflecting the genetic makeup of the founders.

Question 9

What is the fundamental unit of heredity that carries information about specific traits and is a segment of DNA?

Answer 9

Gene

Question 10

What are the different versions of a gene called, such as blue, brown, or green for eye color?

Answer 10

Alleles

Question 11

What term refers to the complete set of genes in an organism?

Answer 11

Genome

Question 12

What is the term for the genetic makeup of an organism, representing the combination of alleles it possesses?

Answer 12

Genotype

The genotype is the genetic blueprint of an organism, which interacts with the environment to produce the phenotype

Question 13

What term describes the observable physical or behavioral characteristics of an organism, such as eye color or height?

Answer 13

Phenotype

The phenotype is the result of the interaction between an organism’s genotype and its environment.

Question 14

What term describes an organism that has two identical alleles for a particular gene?

Answer 14

Homozygous

Homozygous individuals can be either homozygous dominant (e.g., BB) or homozygous recessive (e.g., bb).

Question 15

What term describes an organism that has two different alleles for a particular gene?

Answer 15

Heterozygous

In heterozygous individuals (e.g., Bb), the dominant allele typically determines the phenotype.

Question 16

What term refers to an allele that masks the effect of another allele in a heterozygous individual?

Answer 16

Dominant allele

Dominant alleles are expressed in the phenotype even if only one copy is present (e.g., Bb results in brown eyes if B is dominant).

Question 17

What term refers to an allele whose effect is masked by a dominant allele in a heterozygous individual?

Answer 17

Recessive allele

Recessive alleles are only expressed in the phenotype when two copies are present (e.g., bb for blue eyes).

Question 18

What is the process of cell division that produces sex cells (sperm and egg) and ensures genetic variation in offspring?

Answer 18

Meiosis.

Question 19

What term refers to a permanent change in the DNA sequence that can introduce new alleles into a population?

Answer 19

Mutation

Mutations can be caused by errors during DNA replication, environmental factors, or external agents like radiation.

Question 20

What is the technology called that allows scientists to directly manipulate an organism’s genes?

Answer 20

Genetic engineering

Genetic engineering involves techniques like CRISPR to edit genes, with applications in medicine, agriculture, and biotechnology.

Question 21

What are the thread-like structures found in the nucleus of cells that contain DNA?
Answer:

Answer 21

Chromosomes

Chromosomes are made up of DNA tightly coiled around proteins and carry genetic information in the form of genes.

Question 22

What is the molecule that carries the genetic instructions for all living organisms?

Answer 22

DNA

DNA (deoxyribonucleic acid) is a double-stranded molecule that encodes genetic information using four nucleotide bases: A, T, C, and G.

Question 23

What term describes the differences in genetic material within a population, often resulting from mutations, meiosis, and sexual reproduction?

Answer 23

Genetic variation

The factors that can induce genetic variation are; mutation, gene flow,

Question 24

The main factor that affects Genetic Drift. Which constitutes to the sudden decrease in a population.

Answer 24

Bottleneck effect

A sudden reduction in population size due to a catastrophic event (e.g., natural disaster) can drastically reduce genetic diversity.

Question 25

What are the three main sources of genetic variation in a population?

Answer 25

* Mutation: Introduces new alleles. * Gene flow: Shuffles alleles between populations. * Genetic drift: Randomly changes allele frequencies, especially in small populations.

Question 26

What term describes the fundamental concept of genetics discovered by Gregor Mendel, which explains how traits are passed from parents to offspring?

Answer 26

Mendelian inheritance

Question 27

What term refers to the square diagram used to predict the genotypes of offspring from a particular cross or breeding experiment?

Answer 27

Punnett Square

Question 28

What term describes the method used to predict the outcomes of crosses involving multiple traits, which is often easier than using a Punnett square?

Answer 28

Forked-line method

Question 29

What term refers to the inheritance pattern where a trait is controlled by multiple genes, resulting in a range of phenotypes?

Answer 29

Polygenic Inheritance

Question 29

What term describes the study of how environmental factors can influence gene expression without changing the DNA sequence?

Answer 29

Epigenetics

Question 29

What term refers to the degree of similarity between the alleles for a specific trait in an organism?

Answer 29

Zygosity ## Footnote Zygosity describes whether an organism has identical (homozygous) or different (heterozygous) alleles for a particular gene.

Question 29

What term describes a condition where an organism has only one allele for a particular gene, as seen in males for X-linked traits?

Answer 29

Hemizygosity ## Footnote emizygosity occurs when an organism has only one copy of a gene, such as males with X-linked genes (e.g., X^R Y).

Question 29

What term describes a condition where an organism lacks both alleles for a particular gene?

Answer 29

Nullizygosity ## Footnote Nullizygosity refers to the absence of both alleles for a gene, often resulting in a non-functional or missing trait.¹

Question 29

What term refers to the fertilized egg formed by the union of two gametes, which develops into a new organism?

Answer 29

Zygote ## Footnote A zygote is the single cell formed when a sperm and egg fuse during fertilization, containing the full set of chromosomes needed to develop into a new organism.

Question 30

A farmer grows a field of tomatoes and notices that some plants produce larger fruits than others. The farmer decides to save seeds only from the plants with the largest fruits to plant next year. What process is the farmer using to improve the size of tomatoes over time?

Answer 30

Artificial selection ## Footnote Artificial selection, also known as selective breeding, is the process by which humans intentionally choose organisms with desirable traits to reproduce, leading to changes in the population over generations.

Question 31

In a population of moths, some are light-colored, and some are dark-colored. Over time, the trees in their habitat become darker due to pollution, and the dark-colored moths become more common because they are better camouflaged from predators. What process explains the increase in dark-colored moths over time?

Answer 31

Natural selection ## Footnote Natural selection is the process by which organisms with traits better suited to their environment are more likely to survive and reproduce, passing those traits to the next generation.

Question 32

A population of fish lives in a lake with low oxygen levels. Over many generations, the fish develop larger gills to absorb more oxygen, allowing them to survive better in their environment. What term describes the process by which the fish become better suited to their environment over time?

Answer 32

Adaptation ## Footnote Adaptation refers to the process by which a population evolves traits that improve survival and reproduction in a specific environment.

Question 33

In a population of rabbits, some have longer ears, and some have shorter ears. This difference in ear length is an example of what genetic phenomenon?

Answer 33

Variation ## Footnote Variation refers to the differences in genetic traits among individuals in a population, which is essential for natural selection to occur.

Question 34

Other term for artificial selection

Answer 34

Selective Breeding

Question 35

A population of birds lives on an island where the primary food source is hard-shelled nuts. Birds with larger, stronger beaks are better able to crack the nuts and survive. What term describes the environmental factor (hard-shelled nuts) that favors birds with stronger beaks?

Answer 35

Selection Pressure ## Footnote Selection pressure is an environmental factor that influences which individuals in a population are more likely to survive and reproduce based on their traits.

Question 36

Two populations of the same species of bird are separated by a mountain range. Over thousands of years, they evolve different traits and can no longer interbreed. What term describes the formation of two distinct species from one original population?

Answer 36

Speciation ## Footnote Speciation is the evolutionary process by which populations diverge to form distinct species, often due to geographic isolation or other barriers.

Question 37

A single oak tree produces thousands of acorns, but only a few of these acorns grow into mature trees due to competition for resources like sunlight and water. What term describes the tendency of organisms to produce more offspring than can survive?

Answer 37

Overproduction

Question 38

In a population of deer, some individuals are faster runners due to their genetic makeup. During a predator attack, the faster deer are more likely to escape and survive.

Answer 38

Differential Survival ## Footnote Differential survival refers specifically to the process by which individuals with advantageous traits are more likely to survive in a given environment. It is one component of natural selection, to make it clear.

Question 39

A green caterpillar sits on a leaf, blending perfectly with the color and texture of its surroundings, making it nearly invisible to predators. What term describes the caterpillar's ability to blend in with its environment?

Answer 39

Camouflage ## Footnote Camouflage is an adaptation that allows organisms to blend in with their surroundings, making them difficult to detect by predators or prey. It often involves colors, patterns, or shapes that match the environment.

Question 40

A brown moth rests on the bark of a tree, its coloration and texture perfectly matching the tree's surface. What type of camouflage involves blending with the color and texture of the environment?

Answer 40

Background matching ## Footnote Background matching is a form of camouflage where an organism's appearance matches the color and texture of its surroundings, making it harder to detect.

Question 41

A zebra's black and white stripes break up its body outline, making it difficult for predators to recognize its shape from a distance. What type of camouflage involves patterns that disrupt the outline of an organism's body?

Answer 41

Disruptive Coloration ## Footnote Disruptive coloration uses patterns like stripes or spots to break up the outline of an organism's body, making it harder for predators to recognize its shape.

Question 42

A shark has a dark upper surface and a light underside, making it less visible from above and below in the water. What type of camouflage involves darker coloration on the upper surface and lighter coloration on the underside?

Answer 42

Countershading ## Footnote Countershading is a form of camouflage where an organism's upper surface is darker and its underside is lighter, minimizing shadows and making it less visible from different angles.

Question 43

A harmless viceroy butterfly mimics the appearance of a toxic monarch butterfly to avoid being eaten by predators. What term describes a harmless species mimicking a harmful or unpalatable species?

Answer 43

Batesian Mimicry ## Footnote Batesian mimicry occurs when a harmless species evolves to resemble a harmful or unpalatable species, gaining protection from predators.

Question 44

Two species of toxic butterflies evolve to look similar, reinforcing the learning experience for predators to avoid both species. What term describes two or more harmful species evolving to resemble each other?

Answer 44

Müllerian Mimicry ## Footnote Müllerian mimicry occurs when two or more harmful or unpalatable species evolve to resemble each other, reinforcing predator avoidance behavior.

Question 45

A small group of birds colonizes a remote island, and their descendants have a different allele frequency than the original population.

Answer 45

Founder effect ## Footnote The founder effect occurs when a small group of individuals colonizes a new area, leading to a population with a gene pool that may not represent the original population.

Question 46

In a small population of insects, a rare allele for blue coloration becomes the only allele present after several generations due to random mating. What term describes the process by which an allele becomes the only variant present in a population?

Answer 46

Fixation of alleles

Question 47

In a small population of plants, some individuals with a rare allele for flower color reproduce more frequently by chance, increasing the frequency of the allele in the next generation. What term describes the process by which alleles are passed on due to chance rather than selection?

Answer 47

Random mating ## Footnote Random mating refers to the process by which individuals in a population mate without regard to genotype, leading to changes in allele frequencies due to chance.

Question 48

A scientist observes that a single nucleotide in a gene has been replaced by another nucleotide, altering the protein produced by that gene.

Answer 48

What term describes this permanent change in the DNA sequence? ## Footnote A mutation is a permanent change in the DNA sequence of an organism, which can alter genetic instructions and lead to changes in traits.

Question 49

In a gene responsible for blood clotting, a single base pair is deleted, causing a frameshift mutation that leads to a genetic disorder. What type of mutation involves a change in a single base pair of DNA?

Answer 49

Point Mutation ## Footnote Point mutations are changes in a single nucleotide base pair, which can include substitutions, insertions, or deletions.

Question 50

A segment of a chromosome breaks off and reattaches in the reverse orientation, disrupting several genes. What type of mutation involves large-scale changes to the structure of a chromosome?

Answer 50

Chromosomal Mutation ## Footnote Chromosomal mutations involve changes to the structure or number of entire chromosomes, such as deletions, duplications, inversions, or translocations.

Question 51

During DNA replication, an error occurs that is not corrected by the cell’s repair mechanisms, leading to a change in the DNA sequence. What term describes mutations that occur naturally during DNA replication or repair?

Answer 51

Spontaneous Mutation ## Footnote Spontaneous mutations arise naturally due to errors in DNA replication or repair mechanisms, without external influences.

Question 52

A person exposed to high levels of UV radiation develops a mutation in their skin cells, increasing the risk of skin cancer. What term describes mutations caused by external factors like radiation or chemicals?

Answer 52

Induced Mutation ## Footnote Induced mutations are caused by external agents such as radiation (e.g., UV light, X-rays), chemicals (mutagens), or viruses.

Question 53

While observing meiosis in a fruit fly experiment, a geneticist notices segments of DNA are swapped between homologous chromosomes. What specific process involves the exchange of DNA between homologous chromosomes during meiosis I?

Answer 53

Crossing over ## Footnote Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis, creating new allele combinations.

Question 54

In a plant-breeding study, researchers find that the inheritance of flower color is independent of seed shape. What process results in the random distribution of homologous chromosomes during meiosis, contributing to genetic variation?

Answer 54

Independent assortment ## Footnote Independent assortment occurs during meiosis I when homologous chromosome pairs align randomly, ensuring diverse genetic outcomes in gametes.

Question 55

A scientist observes that offspring in a mouse population show novel combinations of traits not present in either parent. What term describes the exchange of genetic material during meiosis that results in genetic diversity?

Answer 55

Recombination ## Footnote Recombination is the broader process during meiosis where genetic material is shuffled between homologous chromosomes, generating genetic diversity in populations.

Question 56

After years of interbreeding between two animal populations, their genetic makeup becomes nearly identical. What term describes the effect where high levels of gene flow make populations genetically similar?

Answer 56

Homogenization ## Footnote Homogenization occurs when extensive gene flow makes populations more genetically similar, reducing distinctiveness.

Question 57

Wind carries pollen from one population of oak trees to another, resulting in new genetic combinations in the offspring. What example of gene flow involves the movement of pollen between plant populations?

Answer 57

Plant pollination ## Footnote Plant pollination, facilitated by wind or pollinators, allows genetic material to move between plant populations, contributing to gene flow.

Question 57

A herd of deer moves to a new habitat and interbreeds with the resident population, introducing new genetic traits. What example of gene flow involves the movement of animals between habitats?

Answer 57

Animal Migration ## Footnote Animal migration enables genetic material exchange between populations, increasing genetic diversity and facilitating adaptation.

Question 58

A group of people migrates to a new region, contributing to genetic diversity in the local population over generations. What example of gene flow involves the movement of people across geographical regions?

Answer 58

Human Migration ## Footnote Human migration contributes to gene flow by introducing new genetic material into local populations, influencing genetic diversity and evolution.

Question 59

In a bird population, individuals with brightly colored feathers are more likely to choose similarly vibrant mates. What term describes mating that occurs when the probability of two individuals pairing is not equal for all pairs?

Answer 59

Non-random mating ## Footnote Non-random mating occurs when individuals select mates based on specific traits rather than at random, influencing genetic diversity in a population.

Question 60

In a human community, people with similar educational backgrounds are more likely to marry each other. What type of non-random mating involves individuals choosing mates that are similar to themselves?

Answer 60

Positive Assortative Mating ## Footnote Positive assortative mating occurs when individuals prefer mates with similar traits, increasing homozygosity for certain alleles.

Question 61

In a plant population, flowers prevent pollination from closely related individuals by encouraging cross-pollination with genetically different plants. ## Footnote What type of non-random mating involves individuals preferring mates that are different from themselves?

Answer 61

Negative Assortative Mating

Question 62

A small isolated animal population shows an increased prevalence of genetic disorders due to repeated mating among close relatives. What type of non-random mating involves closely related individuals breeding, increasing homozygosity?

Answer 62

Inbreeding ## Footnote Inbreeding involves mating between closely related individuals, which increases the likelihood of recessive genetic disorders and homozygous genotypes.

Question 63

A research team discovers evidence suggesting that organic molecules capable of forming life were found on a meteorite that landed on Earth. What theory suggests that the building blocks of life may have come from another planet?

Answer 63

Theory of panspermia ## Footnote The theory of panspermia (also called exogenesis) posits that life or its precursors arrived on Earth via comets, meteorites, or cosmic dust from outer space.

Question 64

A scientist simulates conditions of early Earth in a lab and observes the formation of amino acids, supporting the idea that life may have originated in a mixture of organic compounds. What theory suggests that life began in a chemical "soup" of organic molecules on early Earth?

Answer 64

Primordial Soup Theory ## Footnote The primordial soup theory proposes that life originated in a mixture of organic compounds and environmental catalysts, leading to the formation of living cells.

Question 65

Scientists find 4.1-billion-year-old fossils of a microbial mat in Western Australia, possibly representing Earth's earliest forms of life. What evidence is often used by scientists to study life forms from Earth's distant past?

Answer 65

Fossils ## Footnote Fossils are the preserved remains or traces of ancient organisms, providing crucial evidence for understanding Earth's history and the evolution of life.

Question 66

A geology professor explains that the Earth's history is divided into distinct periods based on the types of life-forms that existed. What system is used to divide Earth's history into specific time periods based on life forms and rock formations?

Answer 66

Geologic time scale ## Footnote The geologic time scale is a chronological framework used to classify Earth's history into eras, periods, and epochs based on fossil evidence and major geologic events.

Question 67

A geology student is learning about divisions of time such as eras and periods used to represent different stages of Earth's history. What are the divisions of the geologic time scale based on rock formations and the fossil record called?

Answer 67

Geochronologic units ## Footnote Geochronologic units are divisions of time in the geologic time scale, such as eras, periods, and epochs, based on changes in life-forms and rock layers.

Question 68

What is the longest subdivision in the geologic time scale, defined by the abundance of certain fossils?

Answer 68

Eons

Question 69

What subdivision of the geologic time scale comes after eons and is characterized by significant changes in the fossil record?

Answer 69

Eras ## Footnote Eras are major divisions of geological time marked by widespread changes in life forms, often ending with mass extinction events.

Question 70

A paleontologist is analyzing fossils from a time when dinosaurs thrived. What geologic subdivision is based on types of life existing at specific times?

Answer 70

Periods ## Footnote Periods are divisions of geologic time characterized by the types of life forms that were dominant during that time.

Question 71

A scientist uses fossils to correlate and sequence rock layers from different regions. What technique uses fossils as guides to determine the relative age of rock layers?

Answer 71

Biostratigraphy ## Footnote Biostratigraphy uses index fossils—species with a wide distribution but a short time span—as guides to identify chronostratigraphic units.

Question 71

What is the shortest subdivision in the geologic time scale marked by differences in life forms?

Answer 71

Epochs ## Footnote Epochs are the smallest divisions of geologic time, often defined by local differences in fossil life forms.

Question 72

A geologist wants to determine the exact age of a volcanic rock sample in years. What dating method assigns a specific age to a rock based on the properties of its atoms?

Answer 72

Absolute Age Dating ## Footnote Absolute age dating uses radioactive decay to assign precise ages to rocks, unlike relative dating, which only sequences events.

Question 73

A scientist is dating a 5,000-year-old piece of ancient wood. What dating method measures the decay of carbon-14 to determine the age of once-living materials?

Answer 73

Radiocarbon Dating ## Footnote Radiocarbon dating measures radiation emitted by decaying C-14 isotopes and is effective for dating materials up to about 70,000 years old.

Question 74

A geologist finds a rock feature that cuts through several older rock layers. What principle states that a rock feature cutting across another must be younger than the feature it cuts?

Answer 74

Principle of cross-cutting relationships ## Footnote This principle asserts that any geological feature that cuts across other layers is younger than the layers it intersects.

Question 75

rock contains fragments of a different type of rock embedded within it. What principle states that rock fragments included within another rock must have formed first?

Answer 75

Inclusion Principle ## Footnote The inclusion principle states that fragments of rock within a second rock type must predate the formation of the enclosing rock.

Question 76

A geologist uses current volcanic activity to explain past volcanic eruptions. What theory suggests that the present is the key to understanding Earth's past geological processes?

Answer 76

Uniformitarianism ## Footnote Uniformitarianism, proposed by James Hutton, holds that current geological processes have operated throughout Earth's history.

Question 77

A paleontologist is studying different rock layers and noting that they contain similar fossil assemblages. What principle states that rock layers can be identified by the fossils they contain, and these fossils occur in a consistent order through time?

Answer 77

Principle of biologic succession ## Footnote The principle of biologic succession, developed by William Smith, states that fossil assemblages in rock layers are unique and can be used to identify and correlate strata across different regions.

Question 78

Who was the geologist that published "Principles of Geology" and introduced ideas like the principle of cross-cutting relationships and uniformitarianism?

Answer 78

Charles Lyell

Question 79

Who is the geologist credited with developing the theory of uniformitarianism and believed that the Earth’s surface was constantly changing?

Answer 79

James Hutton ## Footnote James Hutton, a Scottish geologist, is considered the father of modern geology, proposing the theory of uniformitarianism, which emphasizes that the processes we observe today have shaped the Earth throughout its history.

Question 80

Who is the surveyor who first used fossil assemblages to identify and correlate rock layers over vast distances?

Answer 80

William Smith ## Footnote William Smith, an English surveyor, is credited with developing the principle of biologic succession, using fossils to correlate strata and establish the relative ages of rock layers.

Question 81

Who is the naturalist credited with developing the theory of natural selection and proposing that species evolve over time?

Answer 81

Charles Darwin ## Footnote Charles Darwin, along with Alfred Russel Wallace, is famous for developing the theory of natural selection, which explains how species evolve over time through the survival and reproduction of individuals with favorable traits.

Question 82

What is the estimated age of Earth, and what were the early conditions like?

Answer 82

**4.54 billion years** old, with early conditions characterized by intense heat, volcanic activity, and frequent asteroid impacts.

Question 83

What were the earliest known life forms, and when did they appear?

Answer 83

Single-celled microorganisms (prokaryotes) appeared around 3.5 billion years ago. ## Footnote The earliest life forms were prokaryotes, which lacked a nucleus and were likely similar to modern bacteria and archaea.

Question 84

What evolutionary development revolutionized Earth’s atmosphere by releasing oxygen?

Answer 84

Photosynthesis by cyanobacteria. ## Footnote Photosynthesis by cyanobacteria introduced oxygen into Earth’s atmosphere, paving the way for aerobic life forms

Question 85

Around 2.4 billion years ago, oxygen levels in Earth’s atmosphere increased dramatically, leading to significant environmental changes. What event marked a dramatic increase in atmospheric oxygen around 2.4 billion years ago?

Answer 85

The Great Oxygenation Event ## Footnote The Great Oxygenation Event was a period when oxygen produced by photosynthetic organisms accumulated in the atmosphere, leading to the extinction of many anaerobic species and the evolution of aerobic life.

Question 86

What type of cells evolved around 1.8 billion years ago, leading to greater biological complexity?

Answer 86

Eukaryotes ## Footnote Eukaryotic cells, which contain a nucleus and membrane-bound organelles, evolved from prokaryotic ancestors and enabled the development of multicellular organisms.

Question 87

When did the first multicellular organisms appear, and what major event followed?

Answer 87

Around 600 million years ago, followed by the Cambrian Explosion. ## Footnote The Cambrian Explosion, around 541 million years ago, was a period of rapid diversification during which most major animal phyla appeared.

Question 88

During the Proterozoic Eon, Earth’s land masses gathered to form a supercontinent. What major geological and biological events occurred during the Proterozoic Eon?

Answer 88

Formation of Rodinia and oxygen production by cyanobacteria. ## Footnote The Proterozoic Eon saw the formation of supercontinents and the rise of oxygen-producing cyanobacteria, which transformed Earth’s atmosphere.

Question 89

During the Archean Eon, Earth’s interior was still hot and active. What characterized Earth’s surface during the Archean Eon?

Answer 89

Volcanic activity and the formation of small islands.

Question 90

What were Earth’s surface conditions like during the Hadean Eon?

Answer 90

Molten surface with oceans of liquid rock and boiling sulfur. ## Footnote The Hadean Eon was a time of extreme heat and volcanic activity, with no solid crust or stable atmosphere.

Question 91

What event marked the rapid diversification of animal life around 541 million years ago?

Answer 91

The Cambrian Explosion.

Question 92

What is the correct chronological order of the major eons in Earth's history?

Answer 92

Hadean, Archean, Proterozoic, Phanerozoic

Question 93

What are the three periods of the Cenozoic Era in chronological order?

Answer 93

Paleogene, Neogene, Quaternary

Question 93

What era is known as the "Age of Mammals," spanning from 66 million years ago to the present?

Answer 93

Cenozoic Era

Question 94

Which period saw the extinction of large mammals such as mammoths and saber-toothed cats?

Answer 94

Quaternary Period

Question 95

Which epochs belong to the Paleogene Period, and what are their distinguishing characteristics?

Answer 95

* Paleocene (diversification of small mammals), * Eocene (greenhouse-like climate), * Oligocene (cooler climate, glaciers)

Question 96

What periods make up the Mesozoic Era in chronological order?

Answer 96

Triassic, Jurassic, Cretaceous

Question 97

What major environmental and species changes occurred during the Quaternary Period?

Answer 97

Extinction of large mammals and birds, including mammoths and saber-toothed cats

Question 98

What is the geologic era known as the "Age of Reptiles"?

Answer 98

Mesozoic Era

Question 99

What is the correct order of the periods in the Paleozoic Era, from oldest to most recent?

Answer 99

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian

Question 99

In which period did the first birds appear, while dinosaurs flourished during their "golden age"?

Answer 99

Jurassic

Question 100

During which Mesozoic period did the first dinosaurs appear?

Answer 100

Triassic

Question 100

What period first saw land plants and coral reefs emerge?

Answer 100

Silurian

Question 101

What period ended with the mass extinction of most dinosaurs?

Answer 101

Cretaceous

Question 102

What era featured the rise of land plants, marine invertebrates, and the emergence of fish?

Answer 102

Paleozoic Era

Question 103

Which period of the Paleozoic Era is known for the explosion of life?

Answer 103

Cambrian

Question 104

What period in the Paleozoic Era marked the dominance of marine invertebrates like trilobites?

Answer 104

Ordovician

Question 105

Which Paleozoic period is known as the "Age of Fishes"?

Answer 105

Devonian

Question 106

What period ended with the extinction of 90% of Earth's species?

Answer 106

Permian

Question 107

What period featured the first seed plants and reptiles?

Answer 107

Carboniferous

Question 108

Which epoch is the current interglacial period within the Quaternary Period?

Answer 108

Holocene

Question 109

Which period in the Cenozoic Era marked the emergence of kelp forests and grasslands?

Answer 109

Miocene

Question 110

What epoch within the Paleogene Period featured a greenhouse-like climate and the junction of India with Eurasia?

Answer 110

Eocene

Question 111

During which epoch did plants adapt to cooler, seasonal climates as glaciers first appeared in Antarctica?

Answer 111

Oligocene

Question 112

Which epoch of the Paleogene saw the diversification of placental mammals after the Cretaceous extinction?

Answer 112

Paleocene

Question 113

What is the correct order of epochs in the Cenozoic Era, from oldest to most recent?

Answer 113

Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene

Question 114

Which epoch of the Neogene Period was marked by the emergence of apes living on African plains?

Answer 114

Pliocene

Question 115

During which epoch did large predatory mammals and small rodents evolve alongside new bird species?

Answer 115

Miocene

Question 115

What epoch within the Quaternary Period was characterized by alternating glacial and interglacial periods?

Answer 115

Pleistocene

Question 115

How long ago did the Cenozoic Era begin?

Answer 115

66 million years ago

Question 116

How long ago did the Mesozoic Era span?

Answer 116

252 to 66 million years ago

Question 117

How long ago did the Paleozoic Era span?

Answer 117

541 to 252 million years ago

Question 118

How long ago did the Precambrian Era begin?

Answer 118

4.6 billion years ago

Question 119

When did the earliest known life forms, single-celled microorganisms, first appear on Earth?

Answer 119

Around 3.5 billion years ago

Question 120

Around when did the Great Oxygenation Event occur?

Answer 120

Around 2.4 billion years ago

Question 121

When did eukaryotes, complex cells with a nucleus, evolve?

Answer 121

Around 1.8 billion years ago

Question 121

When did the first multicellular organisms appear?

Answer 121

Around 600 million years ago

Question 122

What term describes the gradual change in living organisms over successive generations, often driven by mechanisms like natural selection?

Answer 122

Evolution ## Footnote Evolution is the process by which living organisms undergo gradual changes over successive generations, often driven by mechanisms like natural selection, genetic drift, and gene flow.

Question 123

What term describes the complete disappearance of a species from Earth?

Answer 123

Extinction ## Footnote Extinction is the complete disappearance of a species, which can result from various factors such as climate change, habitat loss, overhunting, and natural disasters.

Question 124

What term describes periods of widespread and rapid extinction of species, often triggered by catastrophic events such as asteroid impacts or volcanic activity?

Answer 124

Mass extinctions ## Footnote Mass extinctions are periods in Earth's history when a large number of species go extinct in a short geological time frame, often due to catastrophic events like asteroid impacts, volcanic eruptions, or rapid climate change.

Question 125

What name is given to the most severe mass extinction event in Earth's history, which occurred around 252 million years ago and wiped out a large percentage of life on Earth?

Answer 125

The Great Dying ## Footnote The Great Dying, also known as the Permian-Triassic extinction, was the largest mass extinction event in Earth's history, resulting in the loss of up to 90% of marine species and 70% of terrestrial species, likely caused by extreme volcanic activity and climate change.

Question 126

During which geologic period did the Great Dying occur?

Answer 126

The Permian Period