exam 2 - bio 114 Flashcards
Monohybrid Cross
mating of two purebred individuals having a trait that is caused by 2 alleles within apopulation yields an F1 generation of heterozygous individuals
Hardy-Weinberg Equilibrium
If more than 2 alleles are present in a population at the same locus, their combination is still a product of the sums of the alleles (p^2 + 2pq + q^2 = 1.0
Bottlenecks
where a pool gene pool is significantly reduced for some reason and a relatively small allele diversity remains
Genetic Drift
constant changing of allele frequencies (that percentage of all alleles any one, or more, allele occupies in a population) in a population over time, due to random mating
Gene Flow
the movement of individuals and their alleles from one population to another
Non-randoming Mating
where individuals are not equally likely to mate with any other individual, but instead choose mates based on specific traits or characteristics, disrupting the expected random mating patterns
Assortative mating
an individual is more likely to mate with another that is similar in phenotype to itself
Disassortive Mating
An individual is more likely to mate with another that has a different phenotype from itself
Inbreeding
mating of individuals that share a recent common ancestor
Inbreeding Depression
inbreeding individuals are likely to share alleles they inherited from their common ancestor
Sexual Selection
special case of natural selection that favors individuals with traits that increase their ability to obtain mates
Sexual Dimorphism
the tendency of two sexes of a species to look different (but not all species)
carolus Linnaeus
creating a set of rules for naming plants and attempting to classify (taxonomic hierarchies)
Bionomial Nomenclature
two descriptive words given to identify a species
Taxonomic Hierachy
system of classifying and naming species for the purpose of understanding and establishing relatedness between species or larger groupings
Species
evolutionarily independent group - mutation, selection, and drift act on the group independently of what’s happening in other groups
Separate Species
if two population do not interbreed in nature, or do so but fail to produce viable offspring
Prezygotic isolation
prevention of individuals from mating and creating a zygote - fertilized egg
Postzygotic isolation
(zygote) offspring of individuals do not survive or reproduce
Morphospecies Concept
differences between groups in size, shape, or other morphological features (sometimes behaviors), indicate the two groups are different species
Phylogenetic Species Concept
reconstruction of the evolutionary history of populations - variety of traits specific to the population in order to establish relatedness between groups, and therefore, distinction between them
Phylogenetic Tree
a branching diagram that depicts relatedness/distinction among groups due to phylogenetic analysis results
Branches
w/in the tree represent a population through time
Nodes
points in time when ancestral group split into 2 or more descendant groups, each group represented by each branch (branches comes together)
Terminal Nodes
the ends of branches that represent a group/species/ or larger - living or extinct
Phenetics
grouping of species by similarity of traits, whether those traits are ancestral or more recently derived
Paraphyletic group
most recent common ancestor and not all of its descendants
Cladistics
grouping of species by shared, recently derived character only
Monophyletic group
most recent common ancestor and all its descendants
Homology
traits are similar due to share ancestry
Homoplasy
traits are similar due to other reasons that common ancestry
Convergent Evolution
the independent evolution(by natural selection) of similar traits in distantly related organisms, where the common ancestor does not have the trait (cause of homoplasy)
Parimony
most likely explanation of pattern is the one that implies the least amount of change
Allopatric Speciation
when subpopulations are separated by some physical barrier
Vicariance
when a population is divided by a change in the geologic landscape, if sub pop. remain separated long enough - allele frequencies will change enough to call them separate species
Dispersal
when a group emigrates from an area, and they are isolated long enough to have allele changes that eventually lead to a new species
Sympatric Speciation
when new species are created in areas where there is no physical barrier between subpop - could interbreed
Reinforcement of species
if pops. can interbreed, produce young, and hybrids have suppressed fitness(sterile/lowered), then selection would favor those that do not interbreed, than further separation will occur
Hybrid zones
areas where 2 pop overlap and hybrids exist - small or large, short-lived or long-lived
New species through hybridization
hybrids contain a unique blend of alleles from parents and therefore diff. characteristics. if these traits can be selected for, then the genes are passed onto the next gen (may cause new species)
Elongated cells
appear in multicellular algae to reach areas with more light
Increased contractile fibers and cytoplasmic streaming
distribute energy products and gases w/in different parts of larger and elongated cells, and between cells, in multicellular organisms
Cellulose, silicon and calcium carbonate
used by the photosynthetic protists to strengthen their cell membranes against predation, while cellulose becoming the common constituent of the cell wall of all land plants
Non-vascular plants without cuticle
purely aquatic, simple plants w/ no major adaptations for existence on land
Non-vascular plants with cuticle
parts of plants out of water have a cuticle that gives dehydration resistance, but lack of support structure (and vascular tissue) results in low, sprawling growth
Vascular, seedless plants
first plant w/ true vascular tissue enabling them to grow to greater heights, reaching above the non-vascular plants to compete for sunlight, but still limited sexually to moist environments b/c of depending on flagellated sperm for reproduction
Vascular, naked-seed plants (gymnosperms)
innovation of pollen and dehydration-resistant seeds enable greater freedom (and dispersal) of sexual reproduction on land but absence (naked) of fruit (ovary) compromises term-45even greater seed dispersal
Vascular plants with fruit-covered seeds (angiosperms)
fruit increases the protection and dispersal of seeds; the largest number of species of all plants
Annuals
die off at the end of the year leaving only seeds for the next growing season
Herbaceous
short-lived and non-woody (little or no lignin)
Root
usually the “below” ground plant part, but more accurately - the plant part not having leaves or nodes
Tap Root system
long central shaft to store nutrients and reach deeper water tables
Fibrous/diffuse root system
primary function is to support plant, secondarily to access a more shallow water supply
Tuber
swollen, energy-storing roots
Adventitious (prop) root systems
root emerges from stem just above ground to help support plants in shallow soils
Snorkel roots (pneumatophores)
emerge below ground but rise above ground to obtain oxygen for respiration w/o the root
Stems/trunks/shoot
above the ground plant part, w/ nodes and leaves
Axial
central column w/ spire shape for strength and shedding snows (spruces)
Dendritic
sub-branching for greater photoreception
Buttressed trunk
for greater support in thin tropical soils
Doubly compound
increases lateral leaf reach w/in mini increase in leaf mass
Needles
giving max water conservation; reduced, but year-round photosynthesis
“primary” cell wall
thin cell membrane similar to animal cells, but also an outer cell wall w/ cellulose
“secondary” cell wall
specialized chemical compunds components corresponding w/ the cell’s specialized function (waxy substances for the cuticle, lignin for maximum strength in xylem tissue)
Meristematic cells
undifferentiated, rapidly-dividing cells w/ just a simple primary cell wall that comprise those layers of active growth (apical - stem & root tips and lateral meristems - cambium).
Parenchyma cells
most common mature cells in the plant, close descendants of meristematic cells, that are less-actively dividing but still totipotent b/c they can either revert back to meristematic tissue or form repair tissue, dermal tissue and ground tissue
Collenchyma cells
much less abundant in the plant; they have longer, thicker, primary cell walls(but no secondary wall) with somewhat more cellulose; they functionterm-65 primarily in support (vascular bundles), but can still stretch and elongate (elongation zones near apical meristems).
Sclerenchyma cells
cells have an extra, “secondary” cell wall impregnated with lignin; these cells do not permit stretching and elongation, and are found in non-growth areas of the tree
Leaf cross section
rom top surface inward, although the majority of stomata are on the underside of the leaf closer to the spongy mesophyll
Wavy cuticles
the cuticle reduces water loss, protects against pathogens , and protects against herbivores
Trichomes
the trichomes thwart small herbivorous insects, reflects excess incoming solar radiation, and conserve water
Stomata (guard cells + pores)
the kidney bean shape guard cells take in water and become turgid(rigid) when moisture is present, opening a pore between them, but become flaccid and close the pore during dry conditions (egulate water vapor(transpiration) and gas passage into and out of the leaf)
Palisade mesophyll
elongated parenchyma cells; site of most photosynthesis
Spongy mesophyll
space for gas and H2O exchange
vascular bundle (in mesophyll)
xylem, phloem and supportive collenchyma cells
cork cambluim
produces cork cells, often w/ lignin, to outside the cork cambium layer
Secondary pholem cells
transport photosynthate, nutrients
Secondary vascular cambium
produces secondary phloem cells to the outside, secondary xylem cells to the inside, and parenchyma cells horizontally (rays) that transport fluids/nutrients between inner and outer cells of the t
secondary xylem cells
active in water transport
sapwood
light-colored xylem layer active in water transport
Heartwood
dark-colored xylem in core of a tree that no longer transports water, but serves as a depot for resin and has anti-microbial and anti-fungal properties
Epidermis with lateral roots and root hairs (waxy cuticle layer reduced)
increase root surface area for water/nutrient absorption
Cortex
parenchyma food-storage cells in the “ground” tissue of the root
Vascular cylinder
in center, or if multiple, dispersed vascular bundles in cortex
Endodermis
important barrier in plant root functioning, site of Casparian strip
Pericycle
layer from which lateral roots begin and grow
Primary growth
caused by apical meristems - increases length of root and shoots
Root cap(loose epidermal cells)
mucigel lubricant secreted to facilitate growth through soil
Apical meristem
a tiny area of undifferentiated, but actively dividing tissue
Primary meristem
just above the apical meristem in the root - cells begin to differentiate
Shoot system
Similar to root tip but with leaves and lateral buds instead ofroot hairs
Secondary growth
caused by lateral meristem (cambium), resulting in increased girth (diameter) of the plant
Lateral meristem
cylinder of actively dividing tissue running the length of the plant and occuring just inside the perimeter of the stem or trunk
Cork cambium
located outside the secondary phloem cells and produces cork Cells (bark) only to the outside of the cork cambium layer; no tissue layer is generated to the inside, (as with the vascular cambium)
Vascular cambium (pt.1)
located inside the cork cambium layer - Produces phloem cells to the outside of the cambium layer; this layer doterm-93esn’t increase in width much because, as new phloem cells are added, older phloem cells disintegrate and are resorbed near the cork cambium
Vascular cambium (pt.2)
Produces xylem cells inside the vascular cambium next to previous xylemt issue, and since old xylem tissue doesn’t disintegrate, the girth of the tree increases. Several cell layers occur each growing season, the spring cells are larger than late summer cells, with the entire seasonal record being one growth ring
Reproductive Zone
flowers, seeds and fruits
Convential Flower
Attracts pollinators, launches pollen, protects ova
Sepals
thicker, leaf-like, photosynthesizing structures that enclose the developing flower bud and other reproductive structures, protecting them from insects and disease
Petals
generally thinner, leafy, colorful, and scented structures located in a whorl inside the sepals, serving to attract pollinators. A nectary at the petals’ base may occur, which contains a nectar reward for pollinators. The entire petal assemblage is termed the corolla.
Stamen
the structure producing the male gametophyte (pollen) and composed of a support shaft (filament) and a terminal pad of pollen (anther)
Carpel
the reproductive structure that produces female gametophytes (and eventually eggs), each composed of a swollen basal ovary with ova, a tubular style, and a terminal stigma upon which pollen lands and initiates the growth of the pollen tube conveying the male gametes to the ova for fertilization
Seed
consists of a plant embryo, an endosperm as a nutrient source, and a seed coat, has a longer lifetime and is less vulnerable to environmental extremes than a eukaryote spore
Fruit
develops from the ovary as the seed(s) develop in the ovary; they function to protect the seed(s) from damage and predators during development, and may aid dispersal as well by attracting predators to eat “ripened” fruit and in the process carry the seeds elsewhere (the seed coat protects the seeds from digestion by the predator, a frugivore
The root (positive) pressure pump: minor factor
all ion/fluid movement in or out of the root has to pass through the endoderm cells’ cytoplasm, which selectively controls which solutes pass into the vascular tissues or out of the phloem into the cortex cells. These endoderm cells drive high concentrations of potassium salts and sugars from the phloem cells to the cortex cells
Endoderm cells
a single cell layer around xylem/phloem tissue in the root) secrete wax on their surfaces
Casparian strip
barrier to all ion/water flow around the endoderm cells
Plasmodesmata
small openings (with intercellular cytoplasmic connections)between the endoderm and cortex cells that allow entry of water into and through the cytoplasm of adjacent endoderm cells
Capillarity
the attraction (adhesion) of water molecules to the sides of tubes (in the vessel elements of the xylem) also contributes to the forces driving water up the xylem
Guttation
the “draw” of water from the leaves stops, and the root pressure can drive some water out the stomata of the leaves of small plants within 2 m of the ground, collecting as H2O droplets on leaf tips
The leaf transpiration negative pressure (tension) pump
major factor
Spongy mesophyll parenchyma cells-stomata
air surrounding the parenchyma cells of the spongy mesophyll is at 100% relative humidity because of “puddles” of water (menisci) coating the cell surfaces. The air outside the leaf almost always has a lower relative humidity
transpiration
wet surface (puddles of menisci) on the spongy
mesophyll cells is required for CO2 to be taken into solution for photosynthesis, and the stomata almost always have to remain open during the day to take in CO2. The result is a net escape of moisture out of the stomata
Translocation
movement of sugars up and down the phloem
the (positive) Pressure-Flow Hypothesis
from the source to the sink area; usually from leaf to root storage
Phloem loading at leaf
From Palisade parenchyma cells to the companion & sieve-tube cells of the leaf phloem
Phloem unloading
movement of sugar in the root phloem to the root companion cells and then to the cortex cells of the root where the sugar is stored
Essential nutrients
required for metabolism or new tissue
Hydroponic techniques
used to determine the exact concentrations of nutrients required for maximum health
Macronutrients
required in relatively large quantities and are the building blocks of nucleic acids, proteins, phospholipids, etc
Oxygen, carbon, and hydrogen
available from the atmosphere or water; oxygen and carbon combined make up 90% or more of the dry weight of a plant
Nitrogen, phosphorus and potassium
acquired from the soil and generally are considered to be limiting nutrients (shortage of them often occurs andresults in reduced growth/reproduction)
Micronutrients
required in relatively small amounts, and usually function in association with enzymes, e.g., chlorine, iron, manganese. These are required in such small amounts that in nature they are seldom “limiting” (= limit growth)
Active Transport
on concentrations are usually higher in plants than the surrounding soil, requiring epidermal cells to actively transport the desired ions against a concentration gradient of those ions into the root cortex otherwise these ions would diffuse out into the so
“salting out”
If certain ions like sodium or calcium become too concentrated in soils, they can draw water out of the roots by osmosis, even in saturated soils, causing plant death
Mycorrhizal fungi symbionts
greater surface-to-volume ratio, supply N,P, K & H20 in high concentrations to plants by wrapping their hyphae closely around the root epidermal cells or actually invading the cell walls of the roots. Greater than 90% of vascular plant species have such symbionts
root hairs
maturation zone of roots increase the surface area for nutrient uptake
acid soild
shut down respiratory decomposition and therefore the release of nutrients from dead organisms
Rapid decomposition by microbes
in tropical soils generates high CO2 levels, which is converted into carboxylic acid that lowers soil pH
leaching
Low pH combined with high precipitation causes — away of soil nutrients, leaving only those elements that are most resistant to acid leaching: iron oxide, hence reddish (laterite) soils
very sandy soils
even without low pH, favor leaching because water flows through easily
very fine, clay soils
favor positive ion retention and adhesion to the clay particles, which attract positive charged ions like N, K and P, making them less available to the plant
saturated soils
do not permit O2 to enter the soil from the air
Heterotrophic lifestyle
deriving nutrition by consuming other life forms
flexiable cell membrane
like plant cells, but unlike them in that plant cells are surrounded by a cell wall made rigid by cellulose and associated Extracellular Matrix (ECM)
glycogen
a carbohydrate energy storage product (compare to starch in plants)
neuromuscular tissue
Associated with movement. The vast majority of animals show locomotion, at least in their larval stages
No primary germ layer
different looking cells come together and function as a multicellular organism, the cells remain totipotent (e.g., sponges)
Diploblastic
two major germ layers form, from which different structures develop. 1) Theectoderm - the outer layer and 2) the endoderm - the inner layer. The ectoderm gives rise to the skin and nervous system structures, and the endoderm gives rise to the lining of the digestive tract(e.g., Cnidarians)
Triploblastic
Three major germ layers. 1) The ectoderm and 2) endoderm form the same types of structures as in 2 above. 3) The mesoderm (meso-meaning “middle”) gives rise to the muscles, bones, and most organ systems (e.g., all other animals)
Cephalized
development of a “head”
Asymmetry
animal cannot be subdivided into equal, but opposite, halves (e.g., sponge)
Radical Symmetry
condition in which many planes will divide an organism into equal, but opposite halves so long as the plane goes through the center of the animal. These animals have a circular body with equally effective action/response in all directions (e.g., jellyfish).
Bilateral Symmetry
Condition in which only one plane will subdivide the animal into equal halves (e.g., mammals)
Body Cavity
separates internal organs from the body wall, allowing greater maneuverability
Acolomate
No body cavity exists (e.g., flatworms)
Pseudocoelomate
animal has a body cavity without a mesodermal lining of organs, allowing better diffusion of substances inside the organism and better maneuverability. However, a certain amount of rubbing between the organs and body wall occurs in these animals (e.g., nematodes)
Eucoelomate
Animal has a body cavity and internal organs covered with a membrane derived from mesoderm. This form provides the best protection from rubbing and foreign antigens entering the coelom from a wound. This condition is found in most higher organisms.
Protostomes
Within the triploblastic organisms, the fate of the embryonic blastopore helps to distinguish phyla. Those that have the blastopore resulting in a mouth
Deuterostomes
those where it becomes the anus
