Exam 2 Flashcards
Plants and their environment – what plants cue in on
which direction is up and which is down
when to germinate, when to remain dormant
when they are old enough to reproduce sexually
needs to know the right time of year for blooming, and the right time for producing fruit
needs to know when to open
if they are being attacked by animals, fungi, viruses, and so on, and then produce protective chemicals
Roots and shoots must coordinate with each other
Newly formed embryos need to inform the plant that they exist and need not only nutrients, but also the protection of a surrounding fruit or cone
Flowers and pollination
Some flowers are pollinated by insects that land on them and then crawl inside; many such flowers orient themselves to be horizontal, aligned with the flight pattern of their pollinators
Abscission zone
(where a piece of the plant falls off) needs to know when to remain dormant and when to be active so that healthy leaves and immature fruits are retained but old ones are allowed to fall off
Environmental Stimuli: gravity, touch, temperature, light, chemical
Gravity indicates the direction of “up” and “down” for plants and their roots ◦ It also causes plants and organs to have weight. The heavier something is, the more strengthening tissues it needs
Touch can illicit a response in plants Examples: venus fly trap, mimosa plant, tendrils
Temperature is an important stimulus for plants in temperate environments that undergo freezing temperatures
Light not only is an important source of energy, but also carries information about the time of year shorter days in winter, longer days in summer ◦Help indicate for the plant which direction is “up” – towards the light!
Phototropin
a pigment that perceives the direction of light and directs plants in that direction
Phytochrome
A pigment called phytochrome detects light for measuring day length
Vernalized
Biennial plants need to be exposed to cold/freezing temperature (to be vernalized) – to know that they are passing from their first year (vegetative state) to their second year (reproductive state)
Transfer of information from plants: hormones
allow molecules to carry information from one area of a plant to another. All plant hormones are involved in numerous responses, none triggers just a single, specific response
Auxins, gibberelins
Auxin helps activate dormant buds, stimulates growth, promotes development of embryos and fruits, and prevents leaves from senescing
Gibberellins are involved with stem elongation, seed germination, and several aspects of flowering
Asexual vs sexual reproduction in plants
During asexual reproduction, a single parent produces progeny that are genetically identical to itself
During sexual reproduction the offspring (progeny) are genetically diverse • Each parent produces gametes which are sperm cells or egg cells, that each contain one complete set of genes of that species. • A sperm cell fuses with an egg cell, resulting in the beginning of a new individual, that will have genes that not only differ from its parents but also from its siblings
Asexual Advantages:
Because the parent lived long enough to reproduce, it must be well-adapted to its environment therefore the offspring will be well-adapted too
Asexual reproduction only requires one parent, so plants that are growing in sparse populations and far away from other plants of its species, are still able to reproduce
Reproduction and rapid colonization is possible in isolation
Asexual Disadvantages:
No genetic diversity (if new traits or alleles are needed to survive, they are at at risk of dying and not reproducing)
Not able to adapt to changing environments, and will not be able to reproduce or have their offspring reproduce if conditions change
Sexual Advantages:
Progeny are genetically diverse
Offspring can therefore be even better adapted than the parent
Offspring could potentially colonize environments that one of the parents couldn’t
New conditions and habitat changes may not have such adverse affects than with asexual reproduction
Sexual Disadvantages:
Even though some offspring might be more adapted to their environment, others might be less adapted
Cannot colonize a new site as rapidly because not all progeny are adapted for it
Changes in habitat could still adversely affect progeny
Isolated individuals cannot reproduce
Mitosis vs meiosis
Mitosis creates duplicate copies of a cell’s genes (this is how most cells multiply as an individual grows from zygote/fertilized egg, to adult) ** All outcome cells are diploid, meaning, they have twice the necessary chromosomes
Meiosis is used to ‘shuffle’ the genes when sex cells are made and to ensure that each egg or sperm cell (called a gamete) receives one – and only one – complete set of genes ** Outcome cells are haploid, meaning, they have one set of necessary chromosomes
Haploid vs diploid
Haploid nuclei have one chromosome of each pair
Diploid nuclei have pairs of homologous chromosomes
Methods for asexual and sexual reproduction in plants
Common form of reproduction is fragmentation: • A wide spreading or vining plant grows several meters in length, then establishes its own root system and can survive if detached from the parent plant
Sexual reproduction in angiosperms involves flowers, which produce the necessary cells and structures
In animal life cycles, diploid adults have sex organs that produce haploid gametes, either sperm cells or egg cells, by meiosis
Once egg cells and sperm cells are brought together, the fertilized egg (now diploid) is called a zygote
Sporophyte vs gametophyte stage (which is haploid vs diploid, asexual vs sexual)
Sporophyte stage – where the plant is diploid and produces spores (spore = a single cell that is a means of asexual reproduction)
Gametophyte stage – where the plant is haploid and produces gametes
Pollen
sperm cells
eggs
egg cells (both gametes)
How plants avoid self-fertilization
In some plants with bisexual flowers, the stamens and carpels mature at different times or are structurally arranged in such a way that it is unlikely that an animal pollinator could transfer pollen from the anthers to the stigma of the same flower
Fruit development
As the ovule develops into a seed, the ovary matures into a fruit. • The stigma and style usually wither away, as do sepals, petals, and stamens. • Fruits are adaptations that result in the protection and distribution of seeds.
Daily changes on earth vs longer scale changes
Daily changes are familiar to us, and have a profound effect on the biology of all organisms
Every 24 hours, there are changes of light and darkness, warmth and coolness
There are seasonal changes of temperature, precipitation, flooding, drought
Changes such as wildfires, earthquakes, landslides, and volcanic eruptions do not occur on a regular cycle, but happen often enough to be familiar to us and impact all forms of life
On longer and larger scales, there are changes that are major but less familiar to us
The continents move across the surface of the Earth, changing their shapes
This changes the shape of the ocean basins, and affects the patterns in which water and air circulate
Mountains build where none were before, and others erode away
Rivers change their courses
At times in the past, earth has been hotter, it has been almost completely frozen over
Earth has gone through eras of humid climate, and eras of dry climate
As these changes occurred, some plants, animals, fungi, and other forms of life were able to adapt
Some individuals had beneficial alleles and even though some of Earth’s changes caused many individuals to perish, those that were adapted to altered conditions survived
Know what alleles are = traits in plants
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Two major extinction periods
(know what likely caused them) MYA = million years ago
Cretaceous Period 65.5 Million Years Ago, a giant asteroid struck Earth and killed most of the living creatures, including the dinosaurs
The Permian-Triassic extinction event occurred 251 Million Years Ago and eliminated 94% of all marine species, and 70% of all land vertebrates
Biogeography definition
the distribution of plants, animals, and other forms of life on Earth, and is heavily influenced by random events
Such events include changes in the size, shape, positions, topography, and climate of the land and water that life inhabits
Millions of years ago, there would have been no way to predict where the continents and oceans would be now, and no way to predict the types of animals and plants that would exist now
3 things that influence biogeography
- Earth’s rotation on a tilted axis – which causes seasons to change during a yearly cycle and which drives massive flows of air in the atmosphere and water in the oceans
- The position of the Earth’s land masses, the continents – when they lie in warm moist areas they are covered with life, but when they drift to inhospitable regions (Antarctica at the South Pole), they become barren
- Origin – The Earth is approximately 4.5 Billion years old. About 470 Million years ago, true plants originated and they diversified as the ground beneath them drifted, and the climate around them changed
How plants on land influenced evolution of animals on land because
animals had to venture onto land to find plants
What would happen if the earth wasn’t tilted?
The sun would rise exactly in the East, pass directly overhead, and set directly in the West ¡ We would have no change during the year, no seasons
Parts of the planet higher than 40 degrees latitude would never have the sun overhead
The equator would be really hot all the time and other regions would receive only oblique lighting
Solstices and when days are longest
At summer solstice, June 21 or 22, the North Pole points directly toward the sun as possible
The days are their longest
By September 23, the autumnal equinox, Earth has made ¼ orbit and the sun is directly over the equator (12 hour light vs. dark at the equator)
Three months later, the winter solstice (December 21 or 22) the South Pole points as directly as possible toward the sun.
The days are their shortest in the Northern Hemisphere, and summer begins in the Southern Hemisphere
Air and oceans distribute heat and moisture slides
Our atmosphere and oceans, being fluids, develop massive flows (currents) when heated in one area and cooled in another
They distribute heat from the tropics all the way to the poles
Solar heat = fuels currents (whether water currents or air currents)
Throughout the year, the water and air receive solar heat, causing tremendous amounts of evaporation
As most air warms, it expands, and rises high into the atmosphere
Once high enough, the air cools, water vapor condenses into rain and calls in torrential storms, producing tropical rainforests in Central America, northern South America, central Africa, and Southeast Asia
Trade winds vs westerly winds
Once back at Earth’s surface, part of the air spreads toward the equator and part flows toward the poles.
Earth’s rotation causes the air moving toward the equator to be deflected westward as a northeast trade wind in the Northern Hemisphere. Air spreading toward the poles from the latitudes is deflected eastward and blows west (called a westerly)
Hurricane vs cyclone
A hurricane is in the Atlantic and Northeast Pacific
A cyclone is in the the South Pacific and Indian Ocean
What causes Santa Ana winds?
The Santa Ana winds originate from high-pressure air masses over the Great Basin and upper Mojave Desert.
The air mass, flowing from high pressure in the Great Basin to a low pressure center off the coast, takes the path of least resistance by channeling through the mountain passes to the lower coastal elevations, as the low pressure area off the coast pulls the airmass offshore.
What el Nino is
The climate phenomenon known as El Niño shows us that weather and climate patterns can be unstable
At irregular intervals between 3 and 7 years, warm water moves eastward along the equator and comes to rest in the eastern Pacific Ocean (near South America)
The warm water evaporates, moves north, providing extra rainfall across the southern United States
El Niño lasts a few months, then weather conditions return to normal
How tectonic plates move and how this is connected to the term continental drift
The Earth’s surface is not static
Moten rock rises from inside the Earth and emerges through volcanoes and fissures
The solid parts of Earth’s crust are broken into giant pieces called tectonic plates
As molten rock rises between the plates, it pushes on them, causing them to slide across the molten rock
This movement is called continental drift
Pangaea, Laurasia, Gondwana
Pangaea – large supercontinent
Laurasia - North America collided with Eurasia
Gondwana – South America, Africa, India, Australia, Antarctica
ALL the biomes (no word bank will be included)
a major category of the world’s distinctive plant assemblages, e.g. the tundra biome, the tropical rainforest biome
Note: mountains are not biomes, but various biomes may be present on one mountain throughout its elevation gradient
Difference between climate and weather
Weather refers to short-term changes in the atmosphere
Climate describes what the weather is like over a long period of time in a specific area
Tropical rain forest
Abundance of resources throughout the year
Biodiversity “hotspots”
Very high species richness
Savanna
Tropical grassland with scattered trees Tree growth and forest development checked by: Limited, seasonal moisture Grazing Fire
Tundra
Permafrost: soil remains frozen throughout the year and is very rich in organic matter
Very low plant diversity:
100 species of vascular plants in High Artic
2 species of vascular plants Antartica
Desert
Little and unpredictable rainfall Low productivity Low species diversity Plant adaptations Drought and frost tolerance Chemical and physical anti-herbivory defenses
Temperate grassland
Very productive biome, in which natural grasses have been mostly replaced by domesticated grasses
Most anthropogenically transformed biome
Temperate forest
Moderate temperature and precipitation
Deciduous and evergreen trees
Soil rich in organic matter
Boreal forest
Coniferous forest or taiga, the largest terrestrial biome in the world
Low diversity of tree flora: pines, firs, spruces
Pest outbreaks
Spruce budworm
Rocky mountain pine beetle
Emerald ash borer
Mediterranean and chaparral
Mild/wet winters, hot/dry summers, and frequent wildfires
