IB bio semester 2 final! Flashcards
(56 cards)
Name and briefly describe the 4 plant groups.
- Bryophyta: mosses, liverworts, or hornworts; no vasculature; reproduction by spores.
- Filicinophyta: ferns; have vasculature and reproduce by spores.
- Coniferophyta: vascular plants; reproduce by naked seeds.
- Angiospermophyta: vascular plants; reproduce by seeds.
These groups represent the major classifications of plants based on their reproductive methods and vascular systems.
Describe vasculature in plants.
Vasculature are the vessels/tubes of an organism; in plants, it consists of xylem (carries water) and phloem (carries sugar).
The vascular system is crucial for the transport of nutrients and water within the plant.
Describe plant structure in dicots.
Dicots have 2 cotyledons within their seed.
- Leaves: waxy cuticle, air spaces, spongy mesophyll, palisade mesophyll, veins/vascular tissues, epidermis, guard cells.
- Roots: epidermis, cortex, vascular bundle/tissue.
- Stem: epidermis, cortex, pith, vascular bundle/tissue.
The structure of dicots is adapted for photosynthesis and nutrient transport.
How is transpiration possible in plants?
Transpiration is the loss of excess water vapor from leaves and stems; liquid water is converted into vapor in spongy mesophyll, diffuses out via guard cells, creating a negative pressure gradient that draws water from xylem.
This process is essential for nutrient uptake and maintaining plant structure.
List the factors that influence the rate of transpiration.
Factors include:
* Humidity (reduces rate)
* Sunlight (increases rate during daytime)
* Temperature (increases rate on hot days)
* Wind (increases rate on windy days)
These factors affect the evaporation of water from plant surfaces.
Write a word equation for photosynthesis.
6CO2 + 6H2O + light energy → C6H12O6 (glucose) + 6O2.
This equation summarizes the process by which plants convert carbon dioxide and water into glucose and oxygen using light energy.
What happens during light-dependent reactions?
Pigments absorb light energy, converting it into chemical energy (ATP); water is split, producing O2 from photolysis.
The energy captured is used in subsequent reactions to produce glucose.
What is the role of pigments in photosynthesis?
Pigments absorb wavelengths of light, driving photosynthesis; chlorophyll absorbs red and blue light best and reflects green light.
The absorption spectrum of pigments is crucial for maximizing energy capture.
Define ecological niche.
The role of a species in an ecosystem, including biotic and abiotic interactions that influence growth, survival, and reproduction.
Understanding ecological niches helps in conservation efforts and ecosystem management.
What are keystone species?
Keystone species are those whose activity has a disproportionate effect on the structure of an ecological community; they control populations and create/alter environments.
The loss of keystone species can lead to significant changes in ecosystem dynamics.
Differentiate between open and closed ecosystems.
An open ecosystem has limitless reservoirs of matter and energy; a closed ecosystem is finite, with all matter accounted for within it.
Examples of closed ecosystems include mesocosms used in ecological studies.
What is primary production?
Primary production is the rate at which producers convert energy into biomass by photosynthesis.
It is a key measure of ecosystem productivity and health.
Explain how energy enters most ecosystems.
Energy enters as sunlight, captured by autotrophs through photosynthesis, converted into chemical energy, and transferred to heterotrophs by feeding.
This flow of energy is fundamental to the functioning of ecosystems.
Name the 4 trophic levels.
- Producer (plant)
- Primary consumer (herbivore)
- Secondary consumer (carnivore)
- Tertiary consumer (carnivore)
Trophic levels illustrate the energy flow and feeding relationships in an ecosystem.
What are the processes that increase CO2?
Processes include:
* Respiration
* Decomposition
* Burning fossil fuels
* Deforestation
These processes contribute to the greenhouse effect and climate change.
What is ocean acidification?
Ocean acidification occurs when increased CO2 dissolves in oceans, changing the chemistry and lowering pH levels.
This poses a threat to marine life, particularly organisms that rely on calcium carbonate.
Define competitive exclusion.
Competitive exclusion is the principle that two species cannot occupy the same niche for an extended period.
It emphasizes the importance of niche differentiation for species coexistence.
What is adaptive radiation?
Adaptive radiation is when one species diverges rapidly into multiple species to adapt to different environments.
This process is a key mechanism of evolution, leading to biodiversity.
What is the greenhouse effect?
The greenhouse effect is the trapping of thermal radiation by atmospheric greenhouse gases, which leads to warming of the Earth’s surface.
It is a natural phenomenon but is intensified by human activities.
Explain the trend for CO2 concentration in recent decades.
There has been a major increase in CO2 concentration in the atmosphere due to human activities.
This trend is closely linked to climate change and global warming.
What are homologous structures?
Homologous structures are anatomical features found in different species that have similar patterns but different functions, indicating common ancestry.
An example is the pentadactyl limb found in mammals, birds, and reptiles.
Describe holozoic nutrition.
Holozoic nutrition involves ingesting food through a mouth, digesting it internally, and absorbing the nutrients.
Examples include herbivores, carnivores, and scavengers.
What is saprotrophic nutrition?
Saprotrophic nutrition involves secreting digestive enzymes in dead organic matter and absorbing nutrients externally.
This mode of nutrition is common in fungi and decomposers.
What is adaptive radiation?
Adaptive radiation is when one species diverges rapidly into multiple species to adapt.
