Chapter 7 Flashcards
lactose
a disaccharide found in dairy products too large to pass through the cells that line the large intestine.
what is lactase and how does it work?
it is the enzyme that breaks down lactose into its monosaccharide components, glucose and galactose, which are small enough to be transported across cell membranes of the digestive tract into the circulatory system, where they are carried to cells to be used for energy processes and raw building materials.
what happens when someone ingests lactose but doesn’t produce lactase?
The naturally occurring bacteria in the gut break down the lactose which produces a variety of molecules – hydrogen, C02, and methane – which leads to a variety of symptoms – gas, bloating, nausea, and diarrhea.
Did humans always usually produce lactose into adulthood? Why or why not?
The majority of human history has consisted of a dependence of milk that disappearance past infancy due to hunter-gatherer diets of primarily meat and wild plants. Past infancy, the lactase enzyme did not need to be produced.
How does natural selection play into the development of large populations developing the lactase enzyme into adulthood?
Prehistoric people that began farming may have also started raising animals for the consumption of their milk and cheese. In colder northern European climates, consuming dairy might have been essential to survival.
what enzyme causes milk to coagulate into curds and then cheese?
rennin
about how much of the world’s population is lactose intolerant?
65-70%
What is the word for people who can digest lactose?
Lactase persistent
What is the rate of lactose intolerance in places where dairy consumption is scant?
up to 95% in places like southern Africa and much of Asia
What is the rate of lactase persistence in places like northern Europe and Scandinavia?
95%. People have consumed dairy here for thousands of years.
Why do lactase supplements need to be taken with the dairy food?
The lactase enzyme needs to come in contact with the lactose in order to break it down.
What is required to make cheese?
Rennin, which is derived from rennet, which comes from the last chamber of a cow’s stomach.
What is the theory standing about how cheese was invented?
Someone left milk standing in a bag made from a cow’s stomach for too long until it curdled.
Individuals evolve, not populations. (T or F)
False. Populations, not individuals, evolve. Natural selection does act on individuals but pops. show the evolution.
Only heritable, genetically coded traits are subject to natural selection. (T or F)
True.
How does the fossil record provide evidence of evolution?
Contains transitional forms of species, like whales with rear legs, and reveals an ordered appearance of life on Earth, with the oldest prokaryotes at the bottom.
biogeography
the study of the geographic distribution of species.
comparative anatomy
Comparisons of the body structures of modern organisms.
Bioinformatics
Bioinformatics employs computational tools to process genetic data.
the units of evolution
populations
qualifications of a population
- can meet and mate
gene pool
a gene pool consists of all versions of all the genes carried by all the individuals in a population.
how does genetic variation in a gene pool arise?
Through genetic mutations.
how does natural selection act on a gene pool?
Traits that enhance survival and reproduction will be represented with increasing frequency in the gene pool.
*gene flow
genetic exchange among populations due to migration
founder effect
when a few individuals migrate to a new, isolated habitat.
bottleneck
when a population is drastically reduced
*genetic drift
a change in a gene pool by chance, like through death or emigration
sexual selection
Sexual selection is a form of natural selection that depends on an individual’s ability to obtain a mate
speciation
the evolutionary formation of new species
macroevolution
genetic change on a large scale
nonbranching evolution
in nonbranching evolution, a single ancestral population changes gradually
branching evolution
in branching evolution, an ancestral population splits into two and those populations form two new modern species.
what happened following the mass extinction of the dinosaurs?
Mammals diversified tremendously.
How many eras of earth’s history do geologists recognize?
4: The Precambrian, Paleozoic, Mesozoic, and Cenozoic.
What happened during the Precambrian? (4.6 bya to 541 mya)
- 6 bya: The Earth formed.
- 5 bya: Oldest known prokaryote fossils
- 1 bya: oldest known eukaryote fossils
What happened during the Paleozoic Era? (541 to 251 mya)
541 mya: explosion in ocean biodiversity
420 mya: plant life begins on land
370 mya: animals migrate to land
251 mya: Mass extinction event
What happened during the Mesozoic era? (251 to 65 mya)
230 mya: First dinosaurs
100 mya: FLowering plants begin to dominate the land
What happened during the Cenozoic era? (65 mya to the present)
65 mya: Mass extinction of dinos and diversification of mammals
200,000 yrs ago: appearance of anatomically modern humans
When did Pangea exist?
200 million years ago
When did diverging tectonic plates begin breaking up the Pangea supercontinent?
100 million years ago
What is a species?
a population that is capable of interbreeding to produce healthy, fertile offspring. However, oftentimes species produce asexually (???)
what keeps organisms from interbreeding, and therefore keep species separate?
reproductive barriers
What are six kinds of reproductive barriers?
behavioral isolation, mating time differences, habitat isolation, mechanical compatibility, gametic incompatibility, hybrid weakness
what is mechanical incompatibility?
Members of different species often cannot mate because their anatomies are incompatible.
gametic incompatibility
The gametes (sperm and egg of different species usually cannot fertilize each other.
what is hybrid weakness?
when Offspring of two species may be unfit, or they may be sterile.
What is an example of hybrid weakness?
When horses and donkeys mate, the result are mules, which are sterile.
graduated model
In the graduated model of speciation, a species acquires small adaptations to its environment over millions of years.
punctuated equilibrium model
In the punctuated equilibrium model,
there are periods of stasis interrupted by occasional bursts of speciation
Cambrian explosion
530 million years ago during a period called the Cambrian explosion, the rate of evolution was an order of magnitude higher than the normal rate.
True or False: all organisms evolve at the same rate.
False. Organisms can evolve slowly over time (graduated model) or in rapid bursts (punctuated equilibrium)
Allopatric Speciation
Occurs when a physical barrier separates a population.
Give an example of allopatric speciation.
The Grand Canyon’s formation created two different species of squirrels produced from a divided habitat.
Sympatric speciation
occurs when quite suddenly due to large-scale genetic changes. (There is no physical barrier.)
Taxonomy
The identification, naming, and classification of species.
All life is classified by cell type into three units, called _____.
domains
What are the three domains?
Bacteria, Archaea, Eukarya
What are the characteristics of the domain Bacteria?
unicellular, found everywhere, some cause disease in humans but most are beneficial
What are the characteristics of the domain Archaea?
unicellular, live in extreme conditions such as those that are hot, salty, or acidic
What are the characteristics of the domain Eukarya?
unicellular OR multicellular, larger more sophisticated cells
the taxonomic hierarchy
starting with a domain, an ordered series of progressively smaller categories that every organism can be placed into
What acronym can you use to remember the levels of biological organization?
Dear Katherine Plaugher Came Over For Good Snacks
In order, the levels of taxonomic hierarchy from most inclusive to least inclusive:
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
How are species identified in the taxonomic hierarchy?
By a binomial scientific name: genus name first, and their species name last. Ex: Panthera tigris
What are the three main mechanisms of evolution in a population?
Natural selection, genetic drift, and gene flow
Charles Darwin made what bold prediction that proved to be true about the what lied in the crust of the Earth?
The existence of transitional forms from which modern forms of species came.
All four-legged animals share what structural characteristics?
Same limb structures and a backbone.
Name the types of animals in order of their appearance:
Fish, amphibians, reptiles, mammals, birds
When did tetrapods first appear?
370 million years ago
DNA analysis and embryo structure show that ____ are tetrapods’ closest living relatives
Fish
When was the Devonian era?
365-385 million years ago
During the Devonian era, what did the Arctic look like?
Swampy, warm, freshwater and filled with diverse aquatic life. (before continental drift, was located at the Equator)
Give an example of a theorized transitional species between fish and tetrapods.
Tiktaalik is a fossil that has eyes on the top of its head, a tetrapod-like fin structure, ribs that suggest the presence of lungs
Why is Tiktaalik important in piecing together transitional history between tetrapods and fish?
It is one of the oldest transitional species to shed light on the history.
What evidence shows that tetrapods came from fish?
- similar embryos
- fossil record shows tetrapod like fish before the appearance of tetrapods
- both are vertebrates
- DNA analysis
