chapter 37 Flashcards
What is an autotroph?
make their own food, usually through photosynthesis
what is a heterotroph?
absorb energy or consume nutrients from another source
Do plants “eat” minerals they obtain from the soil?
No, they absorb minerals to use IN photosynthesis
What is photosynthesis?
the process that converts sunlight, CO2, and water into food for the organism
Do all autotrophs photosynthesize?
No, some are chemoautotrophs (use inorganic compounds in environment)
What is chlorophyll?
photosynthethic material found in chloroplast, helps trap light energy
What light does photosynthesis use?
everything but green
Where does water enter in plants?
roots
how does the plant get CO2?
through their stomata
when does photosynthesis occur?
daytime! when the sun is out
what process occurs in plants at night?
respiration, have to conserve starch until they can do photosynthesis again
where do plants obtain most of their water and minerals?
upper part of the soil
how does soil benefit from living organisms?
living organisms aerates the soil and provides nutrients in their poo
what are the basic physical properties of soil?
texture and composition
what are the 3 different soil types?
largest=sand, medium=slit, smallest=clay
describe sand
better drainage but hard to retain water
describe clay
retains water but no aeration
why is air important?
animals, plants, and bacteria need to respire
how do rock particles get into soil?
mechanical weathering- water freezing in crevices of rock
chemical weathering- weak acid dissolves rock
both- organisms penetrate and grow in rock
what are soil horizons?
soil stratified into layers
what is topsoil?
consists of mineral particles, living organisms, and humus
what is loam?
the most fertile soil type, equal amounts of sand, clay, and slit
why is topsoil the most important for plant growth?
roots dont penetrate farther than topsoil and humus makes the topsoil fertile
what is soil type?
refers to the size ratio of the particles in a sample. depends on the parent rock type, climate (affects weathering), and present organisms
what is humus?
formed by decomposes, it is very rich and fertile soil. it improves soil structure and traps water
what is the b horizon? (subsoil)
contains much less organic matter than the A horizon and is less weathered
what is the c horizon? (parent rock)
composed of mainly partially broken-down rock. some of the rock served as “parent” material for minerals that later helped form the upper horizons
what caused the american dust bowl of the 1930s?
combination of drought and inappropriate farming
what are aquifers?
they are underground water reserves and are the primary source of irrigation water
what is land subsidence?
a gradual settling or sudden sinking of earth’s surface
what is salinization?
the addition of salts to the soil which makes it an unsuitable environment for plants
what is a solution to irrigation?
to use drip irrigation- the slow release of water to soil and plants from perforated plastic tubing placed directly at the root zone. this technique uses less water and reduces salinization
how do soils become depleted or nutrients?
irrigation leaches nutrients and crop harvesting takes them away
what is fertilization?
the addition of mineral nutrients to the oil
what chemical elements are fertilizers enriched with?
nitrogen, phosphorus, and potassium (NPK ratio)
what are the pros and cons of inorganic fertilizers?
pros: more and faster crop growth
cons: manufacture requires fossil fuels, eutrophication occurs