PBIO Flashcards
Life cycles
the series of changes in the life of an organism including reproduction
Mitosis
process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division
Meiosis
process where a single cell divides TWICE to produce four cells containing half the original amount of genetic information
-sex cells
Haploid
the presence of a single set of chromosomes in an organisms cells
-egg and sperm cells are haploid
Diploid
-sexually reproducing organisms are diploid
-presence of two complete sets of chromosomes in an organisms cells
-each parent contributing a chromosome to each pair
Asexual reproduction
-new offspring produced by a single parent
-no fertilization
-no gamete formation
-short
-genetically similar offspring
-mitotic
-ploidy stays the same
-mitosis ONLY
-no meiosis
Sexual reproduction: gametic
-creating new individual using two parent organisms
-gametes (sex cells)
-fertilization (joining of gametes to form organism)
-zygote (cell formed during gametes fusion)
-two parents
-genetic variation
-no mitosis in haploid stage
-haploid stage is when gametes fertilize
-meiosis
Sexual reproduction: sporic
-meiosis
-fertilization
-mitosis in BOTH diploid and haploid stage
-all land plants, some algae
-diploid stage produces spores by MEIOSIS
-spores grow into a haploid stage that produces gametes by mitosis
-gametes fuse to produce zygote that grows into sporophyte
ploidy
number of chromosomes occuring in nucleus of cell
pollination
transferring pollen grains from male anther of flower to female stigma
-before fertilization
fertilization
combining male gamete with female gamete to produce zygote
Coevolution
process of reciprocal evolutionary change that occurs between pairs of species or among groups of species that interact with one another
female parts of a flower
-pistil
-stigma
-style
-ovary
pistil
-female part of flower
-located in center of flower
-made up of stigma, style, and ovary
-stigma is the sticky knob at top of pistil
-attached to long tubelike structure called style
-style connects stigma to ovary
Male parts of flower
-stamens
-surround the pistil
-stamen is made up of two parts: the anther and filament
-the anther produces pollen (male reproductive cells)
-the filament holds the anther up
perianth
-non reproductive (accessory, sterile) part of flower
-consists of floral leaves
-sepal
-petals
-attracts pollinators
Hermaphroditic flowers
-both stamens and pistils
-monoecious (same house)
dioecious
-a plant has either stamens and pistils, not both
-two houses
gynodioecious
-hermaphroditic flower + female flower
Androdioecious
-hermaphroditic flower + male flower
self pollination
pollination occurs within a flower
-pollination occurs between flowers on the SAME plant
Outcrossing
-pollination occurs between flowers on DIFFERENT plants
Self incompatibility
-mechanism to avoid inbreeding
-pollen can be blocked at the stigma surface or during growth to ovule
-plants can recognize their own pollen based on genetic similarity
-pollen MUST be transferred to other plants
mechanisms to avoid inbreeding
-timing of pollen shedding or stigma receptivity
-flower shape
-dioecy (pollen MUST be transferred to other plants)
Animal pollination
-most flowering plants are animal pollinated
-depends on animals to transfer pollen from one flower to another
-more precise than wind pollination
-plants attract multiple pollinators
-generalists are pollinators that visit multiple plant species
-specialists are pollinators that visit a single plant species
wind pollination
- a lot of energy to produce enough pollen for wind pollination
-plants fertilized by wind borne pollen
pollinators
-pollinators are seeking a reward
-nectar (sugar/amino acids)
-oils (provide fat)
-pollen (high protein)
-they are attracted by scent (sweet odor, pheromone) and floral pigments
Pollination syndrome
-suits of flower traits that have evolved in response to natural selection imposed by different pollinators
-bees are red blind but have good color vision besides
-bees typically like blue yellow or white flowers
-coevolution
Directional selection
- on pollinators and plants
-traits on one side of the mean of their population survive better
Seed dispersal mechanisms
-disperse seeds to reduce competition and reduce inbreeding
-water dispersed
-wind dispersed
-animal dispersed (predictable/targeted by feeding on fruits and passing seeds, seed hoarding, or sticking to fur)
seed dispersal cues
-fruits typically provide cues that they are ready to be dispersed
-color change
-odor
-favors dispersal of mature seeds
-coevolution
ecology
study of the distribution and abundance of organisms and the interactions that determine distribution and abundance
scales in ecology
population= all individuals of a given species present in an area
community= all the populations present in a given area
ecosystem= the community together with the abiotic environment in which its set
biome= broad regions of similar ecosystems defined by climatic conditions
Population growth
carrying capacity:
-max # of organisms that an environment can support
-population growth flattens when resources become limiting (birth rate=death rate, no growth)
-exhaust resources: population crashes
-nutrients added: carrying capacity fluctuates
-richer medium: carrying capacity increases
-in a closed system, there are fixed limits
predator prey cycles
1.) prey population booms due to low predator frequency
2.) predator population booms due to abundant prey
3) prey population crashes due to predation
4) predator population crashes due to lack of resources
5) cyclical as resources recover
population growth rate
population growth rate (r) = population birth rate (b) - population death rate (d)
habitat
where an organism lives
ecological niche
a summary of an organism’s requirements in order to practice its way of life
-ecological role of a species in a community
-interaction with other species
limiting factors in plants
-temperature and moisture
Mutualism
both organisms benefit
ex: pollinators and plants
plant and microbe mutualism
-fungi and bacteria in soil provides nutrients to plants
competition
both organisms cost
-results in reduction of reproduction or survival
-Gause’s Law is competition exclusion principle
-two species competing for the exact same resources cannot stably coexist
Predation/parasitism
-herbivory: consumption of plants by animals
-parasitism: fungal pathogen on soybean
-parasites: live in or on members of another species absorb nutrients/energy from hosts
commensalism
positive effect on one species but no effect on the other species
succession
-the process of change in the species structure of an ecological community over time
-primary succession: on non vegetated land (glaciers retreating, volcanic eruption)
-secondary succession: on previously vegetated land (soil present: abandoned farmland, after deforestation)
ecosystem: energy and nutrients
-energy flows through ecosystems, entering as light and leaving as heat
-nutrients cycle through ecosystems
flow of energy
food chain- description of the flow of energy through an ecosystem
trophic level- species grouped on the basis of what they eat (larger # organisms at lower trophic levels)
1) sun
2) primary producers
3) primary consumers
4) secondary consumers
5) tertiary consumers
6) decomposers
Food chain
description of flow of energy through an ecosystem
-food web is better
nitrogen cycle
-most abundant element in atmosphere
-not in a form that plants or animals can use
-need nitrogen to make protein, dna, and atp
matter
matter cycles through ecosystems through biotic and abiotic pools
