Exam 4 Flashcards
What do scientists believe was the original genetic material able to copy itself without assistance?
RNA
The main hypothesis about the origin about of the first living organisms is called______
biogenesis
What does the term biogenesis mean?
Formation of life from nonliving chemicals
What are the main steps of biogenesis, in the correct order?
Monomers, polymers, self-replicating molecules, first cells
Binary fission produces ______
two genetically identical bacterial cells
Bacteria that have a spherical shape are called _______
coccus
By what means do prokaryotes typically divide?
Binary fission
Which protective structure forms to protect certain bacteria during periods of harsh conditions?
Endospore
If you look at unknown cells under a microscope, what could lead you to correctly conclude that they are prokaryotic cells?
They lack a nucleus
Prokaryotic organisms are present in how many domains?
Two
Which organisms contain the smallest, least complex cell types?
Bacteria
What do the following groups of organisms have in common: methanogens (methane-producing organisms), halophiles (salt-loving organisms), and the thermophiles (heat-loving organisms)?
They are all archaea
Where would you expect to find methanogens?
In the digestive tract of cows
Halophiles are a type of ______
Archaea
Where fo you expect to find thermophiles?
In hot environments
Which organisms are called extremophiles and flourish mostly in extreme conditions?
Archaea
Which one of the following soil-borne organisms can convert atmospheric nitrogen gas into ammonium and other nitrogen compounds that can be taken up and used by plants?
Nitrogen-fixing bacteria
The practice of using bacteria to remove pollutants from the environment is called _____
Bioremediation
Food poisoning is often caused by a bacterium called ______
Salmonella
Which was first on the planet, prokaryotes or eukaryotes?
Prokaryotes
Which statement is true regarding bacteria?
Some bacteria are pathogens and harmful to humans, whereas lots of bacteria are helpful to humans.
Nitrogen-fixing bacteria convert atmospheric nitrogen (N2 gas) into ammonium (NH4). Why is this conversion important for life on Earth?
Ammonium is a very important plant nutrient
Which of the following is a way in which bacteria help the environment?
All of the above ways in which bacteria help the environment
Pathogen is ______
A name given only to bacteria that cause serious illness in humans
The process of _____ occurs when a bacterium internalized bits of DNA from its environment
transformation
A _____ is a small circular molecule of DNA that reproduces independently of the larger bacterial chromosome
plasmid
Most bacteria (and many other single-celled organisms) reproduce via ____ ______, the process of dividing a cell in half, yielding two genetically identical offspring cells
binary fission
The process of ____ involves the building of a physical bridge between two bacteria. DNA then moves across this bridge from a donor cell to a recipient cell.
conjugation
The process of ______ involves the transfer of DNA from one bacterium to another by a virus
transduction
How foes a bacterial ell obtain new DNA during the process of transformation?
Naked DNA from the surrounding environment is taken up by a bacterium.
Viruses that infects bacteria are called _____
bacteriophages
Which is NOT a method bacteria use to generate new combinations of genes?
Binary fission
Bacteria reproduce asexually via binary fission. This process generates _____
Genetically identical bacteria
Which method of bacterial DNA transfer involved a physical connection between the 2 bacterial cells?
Conjugation
What are plasmids?
Small, circular DNA molecules that contain just a few genes and that can be passed on to other bacteria
How long did it take in the history of life on Earth to go from the first prokaryotic cells to the first eukaryotic cells?
Over a billion years
Which eukaryotic structures are thought to have been the result of extensive inward folding of the plasma membrane of an ancestral prokaryotic cell?
The endoplasmic reticulum
What is the leading scientific hypothesis explaining how the endomembrane system of eukaryotic cells originated?
From the inward folding of the plasma membrane
When did the first eukaryotic cells from?
2.1 billion years ago
How did mitochondria and chloroplasts arise in eukaryotic cells?
Via endosymbiosis, where mitochondria and chloroplasts were independent prokaryotic organisms that were engulfed by a larger cell
Based on the endosymbiosis theory that highlights where chloroplasts come from, how would you expect chloroplasts to divide when a plant cells divides?
Via binary fission
What might be the advantage to an ancestral cell if it maintained a photosynthetic bacterium when its cytoplasm rather than digest it?
It could now use photosynthesis to make its food
Which of the following organisms is a prokaryote?
a bacterium
The important distinction between prokaryotes and eukaryotes is that prokaryotes ____ a nucleus, whereas the cells of eukaryotes ______ a nucleus.
lack; have
Protists are _____
all eukaryotic
Which protist group includes members with plantlike traits such as chloroplasts and multicellularity?
Algae
By what means do amoebas and slime molds move?
Pseudopodia
All protists are unicellular organisms
False
Approximately when did the earth’s crust solidify?
4 billion years ago
Which began first?
Multicellular life in the ocean
How long ago did the first humans appear on earth?
2.5 million years ago
What are the steps toward multicellularity, in the correct order?
First a colony of protists forms, then some protists start to specialize in specific tasks, and finally some cells become gametes
An organism is considered truly multicellular when _______
its cells cannot survive on their own
Although generally not considered to be alive, a _____ is studied alongside other microbes such as bacteria
virus
The protein coat that surrounds the nucleic acid of a virus is called a _____
capsid
The _____ _____ is a viral life cycle that results in bursting of the host cell
lytic cycle
The _______ _____ is a viral life cycle in which the virus inserts its genome into the genome of its host, where it may remain dormant for long periods
lysogenic cycle
A _______ is a viral genome that has inserted itself into the genome of its host
prophage
A _______ is a virus that specifically infects bacteria
bacteriophage
Which viral life cycle would result in a quicker death for an infected cell?
the lytic cycle
Which of the following do NOT get infected by viruses?
Animals, plants, and bacteria can all be infected by viruses
The introduction of smallpox to the Americas by Europeans in the colonial era devastated populations of Native Americans. However, now very few people are vaccinated against the smallpox virus. Why?
Smallpox virus has been eliminated from the earth by vaccination of most of the people alive today
Although most biologists do not consider viruses to be alive, viruses do share some characteristics with living things. Which of the following is the requirement for life that viruses lack?
The ability to reproduce on their own
How do viruses make copies of themselves
By using the cellular machinery of the host cell they infected
Which specific cells are infected by the HIV virus?
Helper T cells
How does AZT fight AIDS?
It blocks enzymes that converts viral RNA to DNA (called reverse transcriptase, or RT)
Where would you find double-stranded HIV DNA an infected cell?
Incorporated directly into the host cell’s DNA
Patients with advanced AIDS often die from infections that do little harm to healthy people. Why?
HIV infects and destroys the helper T cells of the immune system
HIV has an RNA genome that is converted to DNA when infecting a human immune cell. This type of virus is called a ______
retrovirus
Which of the following pathogens causes mad cow disease?
A prion
The misshapen version of a protein that causes properly folded proteins to misfold is called a ______
prion
Which of the following infects only plants?
Viroid
A degenerative brain disorder transmitted by cannibalism is called ______
kuru
An infectious circular piece of RNA that can infect plants is called a _____
viroid
What is the most recent common ancestor of fungi and animals?
a protist
All are fungi prokaryotes?
No, they are all eukaryotes
Humans are most related to fungi than to plants.
True
what is a major role that fungi play in ecosystems?
Recycling nutrients from dead organisms back into the food chain
Which of the following is a fungus?
All of the above are types of fungi
What is the primary component of fungal cell walls?
Chitin
Fungi are made of bundles of threadlike _____
hyphae
Which statement regarding fungal reproduction is true?
Many fungi can reproduce either sexually or asexually
The edible portion of the mushroom is the _______
above-ground reproductive structure
How do fungi reproduce sexually?
By the fusion of the haploid cells from two different fungi
Fungi spores are haploid; what distinguishes haploid spores?
Haploid spores have a single set of chromosomes, half the number of chromosomes of diploid organisms
In what way are plants similar to algae?
Both can do photosynthesis
What are the charophytes?
A type of algae that are the closet living ancestors of the first plants
How does a plant’s cuticle allow it to live on land?
by preventing water loss
If a fungicide was applied near a plant, how might it kill the plant?
By killing the fungus associated with the plant’s roots
What are some challenges land plants face compared to life in the water?
All of the above are challenges faced by land plants
What characteristic do plants, algae, and some bacteria have in common that is not shared with fungi or animals?
They can do photosynthesis
Fungicides are used to treat fungal diseases of plants. However, experts have warned gardeners that application of a fungicide can sometimes kill the plant as well as the fungal disease. Propose an explanation for how this might happen?
Fungicides might kill fungi that are part of the plant’s mycorrhizae
What are two types of symbiotic relationships in plant roots?
Bacteria in root nodules, fungi in mycorrhizae
Where do plants typically store their starches and sugars for later use?
In the roots
Why are roots essential for terrestrial plants?
They absorb water and nutrients needed for growth
The ______ tissue system is the tissue system that forms a layer of outer protection for the plant (analogous to human skin)
dermal
The _______ tissue system is the tissue system that forms a long-distance transportation system for the plant (analogous to the human circulatory system)
vascular
The ______ tissue system is the tissue system that is the bulk of the plant, containing tissues that do not belong to the other two tissue systems
ground
Water-conductive cells form a tissue called the _______
xylem
Cells that conduct sugars and other nutrients form a tissue called the _____
phloem
The _____ are small pores in the dermal tissue system that allow for gas exchange
stomata
The ___ ____ control the opening of the gas-exchanging pores in the dermal tissue system
guard cells
The ground tissue of a leaf, which is the primary site of photosynthesis, is called ______
mesophyll
if the phloem in a tree trunk were to become blocked, how would this affect the plant?
Sugars could not be transported from leaves to roots.
In which tissue system of plants would you expect to find the guard cells?
dermal tissue system
what are the three tissue systems of plants contained in each plant organ, such as leaves?
dermal, ground, and vascular tissue systems
All plant organs (such as leaves, roots, and stems) contain tissues from all three tissue systems.
True
What is the order in which the four major groups of plants evolved, from the most ancient to the most recent origin?
Bryophytes, seedless vascular plants, gymnosperms, and angiosperms
What do gymnosperms and angiosperms have in common?
Seeds
Which of the following is the most recent plant adaptation to have evolved?
Flowers
All plant life cycles consists of an alternation of generations. What is the haploid stage of plant life cycle called?
gametophyte
What does gametophyte produce?
Haploid gametes
while mosses can cover a significant area of land, they are never more than a few centimeters tall. Why do they not grow tall?
They have no vascular system, so they cannot transport water over long distances
Why must mosses live in moist environments?
Because they depend in water to reproduce
Which of the following terms describes water molecules sticking to other water molecules?
cohesion
The loss of water from plants through transpiration
is an important part of the mechanism that pulls water from a plant’s roots to its leaves
Which of the folloeing describes the correct order in which water moves through a plant and into the atmosphere?
Root, xylem, leaf cells, air space inside leaves, outside air
The function of a root hair is to
increase the surface area available for absorption in plant roots
which of the following allows plants to be selective about the molecules that enter the xylem?
A waxy barrier in the plant root
Water exits a plant through pores called _____. surrounding each pore is a pair of cells called _____ _____ that regulates the opening of the pore.
stomata; guard cells
Xylem sap is moved through a plant’s body by the process of _____, which relies on the evaporation from the leaves to pull water up the body of a plant.
transpiration
within phloem tissue, glucose and other sugar are always transported from an _____ ____, a part of the plant where sugar is stored or produced, to an ____ ____, a part of the plant where sugar is used.
sugar source; sugar sink
there are two types of vascular tissue within plants. Water and minerals are transported from the roots to the rest of the plant in ____, while sugars are transported from one part of the plant to another in ______
xylem; phloem
The ____ ____ system is a series of tubes within the body of plant through which water, minerals, and sugars are transported
vascular tissue
The xylem is made from _____
dead, hollow cells
The xylem primarily transports ______, while the phloem transports _______
water and minerals; sugars
What kinds of plant were transformed into coal?
ferns and their relatives
ferns often have small bumps arranged in rows on their undersides. What are these structures?
Spore capsules
The tall ferns that we typically see in the tropics and temperate woodlands are the ____
sporophytes
What role does lignin play in a plant’s adaptation to life on land?
it strengthens the cell wall to allow plants to stand up straight and tall
Which is NOT an adaptation of the gymnosperms
flowers
why do pine trees have two different types of cones
one type produces ovules, the other type produces pollen
Which statement related to gymnosperm reproduction is true?
Spores produce pollen grains, which contain sperm.
Not all plants have seeds. What main advantage do seeds provide a plant?
Seeds allow plants to be independent of water for reproduction
Why are gymnosperms no longer restricted to moist environment, as are ferns and mosses?
Because they have a new adaptation, seeds, that allow gametes independence from water
The most important adaptation that differentiates angiosperms from other types of plants is their ________
flowers
What group of plants provides most of our food?
Angiosperms
What plant group has the largest number of living species?
Flowering plants
Most of our food crops come from angiosperms
True
Which type of angiosperm typically has parallel leaf veins and a fibrous root system?
Monocot
What structure of angiosperm attracts animals as a way to disperse seeds?
Fruit
The male part of the flower is the _____
stamen
The pollen tube grows from the ______ to the ______, where it eventually fertilizes the egg.
stigma; ovule
What is a fruit?
A mature ovary
What is the main purpose of flowers?
To attract pollinators
What is the reproductive organ of angiosperms?
Flowers
In the process of _____ _____, a plant lengthens upward toward sunlight.
primary growth
_______ are plants that grow and produce seeds for many seasons before they die
Perennials
The growth rings of a tree occur during _____ ____, the thickening of a plant over many growing seasons
secondary growth
All growth of a flowering plant takes place within specialized tissues called _____
meristems
_______ are plants that sprout from a seed and grow in their first season, and then produce seeds and fruit and die in the next growing season
Biennials
_________ are plants that sprout from a seed, grow, flower, and die all in one growing season
Annuals
In which region of the plant are you most likely to find cells dividing by mitosis?
The meristem region
What causes the annual growth rings of trees?
Different growth rates at different times of the year
A plant that produces flowers and seeds in its second year and then dies is called ______
a biennial
Assuming it doesn’t die unexpectedly, how often would you need to replant an annual plant?
Every year
Root pressure is positive pressure that helps to push water up out of the roots and into the aboveground plant. How is it formed?
Root cells bring mineral nutrients into the root using active transport. This sets up a concentration gradient that draws water into the root by osmosis
Water vapor moves our os leaves through open stomata. This process is known as _______
transpiration
Xylem tissues create a system of very thin pipes that connect plant roots and leaves. Which option best describes the nature and function of xylem tissue?
Xylem is dead tissue. The pipes convey xylem sap from the roots to the leaves. Active transport is not important in moving xylem sap.
Imagine that you spray a large, actively growing tree with a sealant that instantly seals off all of the stomata. What would happen in the xylem system?
The flow of xylem sap would stop, except for some minimal upward movement that might be generated by root pressure
What happens to the xylem system during drought, when water is scarce?
Falling moisture levels in the leaf cause the guard cells to change shape, closing the stomata. This reduces water loss from the plant
which of the following options lists the correct sequence of the appearance of the four major groups of plants in the fossil record, from most ancestral to most recent?
bryophytes, seedless vascular plants, gymnosperms, angiosperms
Which of the following evolutionary adaptations contributed to the ability of bryophytes to colonize land?
waxy cuticle
What is the function of vascular tissue in plants?
to conduct water and nutrients throughout the plant
The main evolutionary advantage of pollen is ________
the ability to transport male gametes without water
Which of the following is an example of an angiosperm?
oak tree
Which classification grouping includes the greatest number of species?
Domain
Of those listed below, which category of classification is the most narrow?
Genus
all prokaryotes are in the domain
Prokaryotes are in different domains
Which grouping includes all of the protists?
Domain Eukarya
What field of science has as its goal to classify all living things into a hierarchical of relatedness that runs from most broad to most narrow?
Taxonomy
The domain Eukarya is divided into kingdoms. Which of these kingdoms includes members that are highly diverse and do not fit neatly into a single classification scheme?
Protists
Some of the “branches” of a phylogenetic tree do not extend to the end. What do these lines represent?
Extinct species
A requirement of cladistics is that a grouping must include ________
A common ancestor and all its descendants
In older classifications schemes, the group called Reptilia was defined as consisting of lizards, turtles, and snakes. Birds were separated into the group called Aves. Why is Aves not a clade?
It does not include the reptiles
