question

Four processes needed for the spontaneous origin of life on Earth

answer

1. Synthesis of organic molecules 2. Synthesis of polymers from organic molecules (water tends to depolymerize molecules) 3. Mechanisms for the self-replication of organic molecules 4. Packaging of these molecules inside of membranes

question

Miller and Urey

answer

Experimentally reproduced organic molecules from hypothesized conditions (gases (methane, hydrogen, ammonia), liquid water (in evaporated and condensed forms), warm temperature, exposure to UV radiation, lightning) of pre-biotic Earth.

question

Possible locations where conditions would have allowed the synthesis of organic compounds

answer

1. Intertidal zones (drying of clay particles, where stromatolites (one of the most ancient forms of life on earth) are found) 2. Deep-sea hydrothermal vents (there is evidence of life) 3. Volcanic areas (rich sources of raw materials, warmth of volcanic activity) 4. Space (presence of glycine, a simple amino acid; comets could have brought organic compounds to earth and their impact on Earth's surface could have facilitated polymerization)

question

Two properties of RNA that would allow it to play a role in the origin of life

answer

1. Able to replicate without the aid of enzymes (unlike DNA) 2. RNA can act as an enzyme (called ribozyme) to facilitate certain chemical reactions

question

Protobionts

answer

Protobionts can maintain an internal chemistry that is different from their surroundings; they protect polymers 1. Proteinoid microspheres (amino acids -> polypeptide chains) can be formed when clay dries out and is heated 2. Coacervate can form spontaneously due to the hydrophobic forces between water and lipid molecules; allows selective permeability

question

Endosymbiotic theory for the origin of eukaryotes

answer

States that the organelles found inside cells today were once independent prokaryotes. Evidence: mitochondria and chloroplasts have characteristics which make them more like independent prokaryotes than organelles Criticisms: 1. Does not explain how the host cell can pass on the genetic code to synthesize the newly acquired organelle to its offspring. 2. Mitochondria and chloroplasts cannot survive on their own when removed from a cell

question

Creation of an oxygen-rich atmosphere

answer

Early photosynthetic prokaryotic organisms started to generate oxygen as a waste product, resulting in an oxygen-rich atmosphere. Autotrophy was an advantage, especially because there was a food shortage, allowing photosynthetic bacteria to proliferate. Evidence: iron was converted into iron oxide (rust) in rocks

question

Effects of an oxygen-rich atmosphere on early life

answer

Oxygen gas killed off large populations of anaerobes. Those that survived were sheltered from the oxygen (in mud, in the guts of living organisms).

question

Half-life

answer

The time it takes for half of a radioactive isotope to decay (for a radioactive isotope to give off half of its original level of radioactivity)

question

Dating rocks and fossils using radioisotopes

answer

Radioisotopes are unstable isotopes that release some of their subatomic particles (alpha and beta) in order to reach a stable state. Radiometric dating is accomplished through looking at the proportion of the radioisotope to other isotopes. Two common radioisotopes are carbon-14 (decays into stable daughter isotope nitrogen-14) and potassium-40 (dating rocks). There are time limits to radiocarbon dating depending on the radioisotope's half-life.

question

Major anatomical features that define humans as primates

answer

1. Opposable thumbs and hands with fingers capable of great dexterity 2. Shoulder sockets capable of complete circular motion 3. Forward-facing eyes giving us stereoscopic vision

question

Possible coexistence of several species

answer

Australopithecus afarensis and australopithecus africanus (plenty of time to encounter each other however very few in numbers) Homo erectus, Homo neanderthalensis, Homo sapiens (Very few in numbers, possible geographic isolation; H. neanderthalensis and H. sapiens probably interacted with each other but never had fertile offspring)

question

Uncertainties about human evolution due to the incompleteness of fossil records

answer

For fossils to be found, they must be physically, politically, and legally accessible, and must be preserved well enough to be identified. Fossils for some species are rare or not well preserved. Estimations about characteristics can be imprecise because of the differences between different members of the population.

question

Changes in brain size during hominid evolution

answer

Change in diet (primarily vegetarian -> partial carnivore) may have evolved with an increase in brain size because a bigger brain requires more energy to function, which requires the consumption of food that is richer in energy and protein (meat, insects). Control of fire, increase in complexity of tools and development of a more complex social system was probably necessary for hunting and consuming meat, and evolved as a result of larger cranial capacity. Counterargument: Neanderthals had larger cranial capacities than modern humans yet they did not have significantly different diets

question

Genetic evolution

answer

Deals with inherited characteristics such as body morphology (cranial capacity, skull shape, height, robustness), number of chromosomes, and particularities of biochemicals (blood proteins). These characteristics must be passed on from parent to offspring genetically.

question

Cultural evolution

answer

Deals with acquired knowledge including language, customs and rituals, art, and technology. These can be passed on through communication.

question

Importance of genetic and cultural evolution

answer

Cultural evolution can sometimes lag behind genetic evolution. Currently though, the pace of cultural evolution has surpassed the pace of genetic evolution for Homo sapiens.

question

Ardipithecus ramidus

answer

5.8 million - 4.4 million years ago (Ethiopia) Long and narrow molars Short (less projecting) canine teeth Bipedalism possible

question

Australopithecus afarensis

answer

4 million - 2.5 million years ago (E. Africa) Tall lower jaw Fairly large molar teeth Projecting face Cranial capacity: 380 - 430 cm^3

question

Australopithecus africanus

answer

3 million - 2.5 million years ago (S. Africa) Tall, thick lower jaw Large molars Projecting face Cranial capacity: 435 - 530 cm^3

question

Homo habilis

answer

2.4 million - 1.6 million years ago (Tanzania, Kenya, Ethiopia, South Africa) Flatter face and larger molars than Australopithecus Cranial capacity: 600 cm^3 (allowed it to use simple stone tools and fire and live in caves)

question

Homo erectus

answer

1.8 million - 100,000 years ago (migratory) Smaller jaw Receding forehead Brow ridges Smaller molars Cranial capacity: 1000 cm^3

question

Homo neanderthalensis

answer

200,000 - 30,000 years ago (Europe, W. Asia) Compared to previous species: Smaller jaw Lower forehead Smaller brow ridges Smaller molars Cranial capacity: 1600 cm^3 (larger than modern humans)

question

Homo sapiens

answer

140,000 - 70,000 years ago (Africa, Europe, Asia) High forehead No brow ridges Flat face Smaller molars Very small jaw Cranial capacity: 1300 cm^3 (developed art in the form of cave paintings and technology in the form of finely crafted tools and weapons)

question

Chronological order of primate species

answer

Ardipithecus ramidus Australopithecus afarensis Australopithecus africanus Homo habilis Homo erectus Homo neanderthalensis Homo sapiens

question

Gene pool

answer

The sum total of all alleles and their frequencies within a population of organisms.

question

Evolution

answer

A change in the frequency of alleles (gene pool) in a population when measured over many generations.

question

Speciation

answer

The formation of new species, initiated when a single gene pool is separated by various kinds of barriers: 1. Geographic isolation 2. Hybrid infertility 3. Temporal isolation 4. Behavioral isolation (moths and pheremones which play a role in attracting and finding a mate)

question

Allopatric speciation

answer

When two or more subsets of a population are geographically separated

question

Sympatric speciation

answer

Speciation in the same geographical area

question

Adaptive radiation

answer

The development of many species from a common ancestor

question

Divergent evolution

answer

When one or more species with dissimilar traits emerge from a single species

question

Convergent evolution

answer

When two or more organisms undergo similar natural selection pressures and evolve to become more and more similar to each other, although the species cannot become the same species.

question

Gradualism

answer

Evolutionary changes are small, continuous, and slow

question

Punctuated equilibrium

answer

Evolutionary changes are relatively quick and then followed by long periods of little or no change

question

Transient polymorphism

answer

Organisms that have two or more forms, which appear depending on the environmental selective pressures at the time. Example: peppered moth during and after the Industrial Revolution

question

Balanced polymorphism

answer

When two or more alleles within a population are stabilized by natural selection. Example: sickle cell anemia because the two forms of hemoglobin (disk-shaped and sickle-cell shaped) have advantages and disadvantages, thus each allele type stays relatively balanced in frequency.

question

Species

answer

Made up of organisms which have similar physiological and morphological characteristics which can be observed and measured, can interbreed and produce fertile offspring, are genetically distinct from other species, have a common phylogeny.

IB Biology SL Paper 3 (Option D)

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards