USABO STUDY GUIDE ACTUAL QUESTIONS WITH SOLUTIONS 2025
GRADED A+
✔✔Meristematic cells - ✔✔Plant version of stem cells
Can specialize into any other type of cells
Actively reproduce by mitosis
Found in:
1. apical (roots & shoots, primary growth)
2. lateral (cambium, secondary growth)
✔✔Parenchyma cells - ✔✔- Thin cell walls (b/c they only have 1 cell wall)
- Found in vascular bundles, leaves, and epidermis
- Loosely packed
- Can specialize into photosynthesis —> chlorenchyma cells
- Can specialize into opening/closing stomata —> guard cells
✔✔Collenchyma cells - ✔✔- Thicker cell wall, but only 1 cell wall
- Found in growing shoots & leaves
✔✔Sclerenchyma cells - ✔✔- Dead cells
- Have lignin & 2 cell walls
- Provide structure
✔✔Biomass pyramid - ✔✔Diagram representing the biomass in each trophic level of an
ecosystem
**can be inverted !!
✔✔Energy pyramid - ✔✔A diagram that shows the amount of energy that moves from
one feeding level to another in a food web
**10% rule !!
✔✔Amphipathic - ✔✔having both a hydrophilic region and a hydrophobic region
polar & nonpolar end
✔✔Ethidium bromide - ✔✔a DNA stain (indicator); glows orange when it is mixed with
DNA and exposed to UV light; abbreviated EtBr
✔✔cathode - ✔✔Negative electrode
✔✔anode - ✔✔Positive electrode
✔✔agarose gel - ✔✔gel matrix used for DNA electrophoresis; big pores
,✔✔SDS-PAGE - ✔✔Type of chromatography used to separate proteins based on mass
✔✔Rank these epochs from oldest to newest:
Eocene, Pleistocene, Miocene, Holocene, Pliocene, Oligocene, Paleocene -
✔✔Paleocene < Eocene < Oligocene < Miocene < Pliocene < Pleistocene < Holocene
✔✔Estuary - ✔✔A habitat in which the fresh water of a river meets the salt water of the
ocean.
✔✔benthic zone - ✔✔the muddy bottom of a lake, pond, or ocean
✔✔pelagic zone - ✔✔open water above the ocean floor
✔✔Stolon - ✔✔a horizontal root that produces new leaves & shoots but NO ROOTS
✔✔Tendrils - ✔✔"climbing" part of plants to attach for support
2 types: stem tendril & leaf tendril
✔✔Rhizome - ✔✔a horizontal, underground stem that produces new leaves, shoots,
and roots
ex. bamboo & ginger
✔✔Shoots vs. Roots - ✔✔- shoot system = stems and leaves
- exist aboveground, capture CO2 and light for photosynthesis
- roots are belowground, absorb nutrients
- transport of sugar from shoots to roots
- transport of water/minerals from roots to shoots
✔✔Bulbs - ✔✔modified stem that stores seeds before they are sent to germinate
ex. garlic, tulip
✔✔Tuber - ✔✔modified stem that stores carbohydrates
ex. potato
✔✔epidermal cells - ✔✔"skin" of plants — outermost cells
Contains waxy cuticle as a barrier to foriegn substances
,✔✔5 causes of evolution - ✔✔shrinking population, nonrandom mating, mutations,
migration, natural selection
✔✔Caffeine is a ___ - ✔✔Diuretic
Caffeine --> inhibit ADH production --> more urine
✔✔Parts of Nephron in order - ✔✔1) Bowman's Capsule
2) Proximal convoluted tubule
3) Loop of henle (descending, ascending) + vasa recta
4) Distal convoluted tubule
5) Collecting duct
✔✔aquaporins - ✔✔membrane proteins that allow water flow
✔✔How does ADH cause water retention? - ✔✔1) ADH/vasopressin binds to outer
receptors on principal cells —> causes mechanims which brings aquoporins to the
membrane of inner collecting duct
2) Water flows out of collecting duct because of a concentration gradient
*Interstitial fluid is hypertonic to urine !!
3) Water goes back to bloodstream through the vasa recta
**ADH acts on collecting duct AND distant convoluted tubule !!
✔✔hypertonic - ✔✔the more concentrated solution
✔✔hypotonic - ✔✔the less concentrated solution
✔✔How do the kidneys deal with hypertonic solution? - ✔✔1) thirst feeling
2) Water reabsorption from urine --> more concentrated urine
✔✔proteasome - ✔✔A giant protein complex that recognizes and destroys proteins
tagged for elimination by the small protein ubiquitin.
Destroys peptide bonds
✔✔Proteolysis - ✔✔decomposition of proteins by destroying peptide bonds
✔✔Proteases - ✔✔enzymes that catalyze proteolysis
✔✔Ubiquitin - ✔✔A protein that attaches itself to faulty or misfolded proteins and thus
targets them for destruction BY PROTEASOMES
✔✔Ubuiquinone - ✔✔Coenzyme Q
, a coenzyme that supports NAD+
✔✔Caspase - ✔✔A family of proteases that, when activated, mediates the destruction
of the cell BY APOPTOSIS
✔✔Kinase - ✔✔an enzyme that catalyzes the transfer of a phosphate group from ATP
to a specified molecule
enzyme that facilitates phosphorylation
✔✔conspecific - ✔✔members of the same species
✔✔probe (genetics) - ✔✔a complementary sequence of ssDNA or ssRNA that can
show when it binds
marked w/ radioactive or chemical tags
✔✔hybridize - ✔✔Two different nucleic acids uniting their complementary sites
✔✔microarray - ✔✔a grid of DNA segments of known sequence that is used to test and
map DNA fragments, antibodies, or proteins
tests how often a gene is expressed
✔✔temperate climate zone - ✔✔Cold winters and mild summers
Moderate rainfall
✔✔Drip tip leaves - ✔✔Leaves that allow water to drip down onto the ground to avoid it
being damaged by high amounts of rainfall.
✔✔sunken stomata - ✔✔reduces water loss as the water has to diffuse a long distance
before it reaches the outside of the leaf
✔✔Succulent leaves - ✔✔modified leaves for water storage
✔✔Dormant buds - ✔✔what most woody plants use to protect their growing tips during
the winter
suppression of growth
✔✔shallow roots - ✔✔take up water quickly after brief rainfall events
GRADED A+
✔✔Meristematic cells - ✔✔Plant version of stem cells
Can specialize into any other type of cells
Actively reproduce by mitosis
Found in:
1. apical (roots & shoots, primary growth)
2. lateral (cambium, secondary growth)
✔✔Parenchyma cells - ✔✔- Thin cell walls (b/c they only have 1 cell wall)
- Found in vascular bundles, leaves, and epidermis
- Loosely packed
- Can specialize into photosynthesis —> chlorenchyma cells
- Can specialize into opening/closing stomata —> guard cells
✔✔Collenchyma cells - ✔✔- Thicker cell wall, but only 1 cell wall
- Found in growing shoots & leaves
✔✔Sclerenchyma cells - ✔✔- Dead cells
- Have lignin & 2 cell walls
- Provide structure
✔✔Biomass pyramid - ✔✔Diagram representing the biomass in each trophic level of an
ecosystem
**can be inverted !!
✔✔Energy pyramid - ✔✔A diagram that shows the amount of energy that moves from
one feeding level to another in a food web
**10% rule !!
✔✔Amphipathic - ✔✔having both a hydrophilic region and a hydrophobic region
polar & nonpolar end
✔✔Ethidium bromide - ✔✔a DNA stain (indicator); glows orange when it is mixed with
DNA and exposed to UV light; abbreviated EtBr
✔✔cathode - ✔✔Negative electrode
✔✔anode - ✔✔Positive electrode
✔✔agarose gel - ✔✔gel matrix used for DNA electrophoresis; big pores
,✔✔SDS-PAGE - ✔✔Type of chromatography used to separate proteins based on mass
✔✔Rank these epochs from oldest to newest:
Eocene, Pleistocene, Miocene, Holocene, Pliocene, Oligocene, Paleocene -
✔✔Paleocene < Eocene < Oligocene < Miocene < Pliocene < Pleistocene < Holocene
✔✔Estuary - ✔✔A habitat in which the fresh water of a river meets the salt water of the
ocean.
✔✔benthic zone - ✔✔the muddy bottom of a lake, pond, or ocean
✔✔pelagic zone - ✔✔open water above the ocean floor
✔✔Stolon - ✔✔a horizontal root that produces new leaves & shoots but NO ROOTS
✔✔Tendrils - ✔✔"climbing" part of plants to attach for support
2 types: stem tendril & leaf tendril
✔✔Rhizome - ✔✔a horizontal, underground stem that produces new leaves, shoots,
and roots
ex. bamboo & ginger
✔✔Shoots vs. Roots - ✔✔- shoot system = stems and leaves
- exist aboveground, capture CO2 and light for photosynthesis
- roots are belowground, absorb nutrients
- transport of sugar from shoots to roots
- transport of water/minerals from roots to shoots
✔✔Bulbs - ✔✔modified stem that stores seeds before they are sent to germinate
ex. garlic, tulip
✔✔Tuber - ✔✔modified stem that stores carbohydrates
ex. potato
✔✔epidermal cells - ✔✔"skin" of plants — outermost cells
Contains waxy cuticle as a barrier to foriegn substances
,✔✔5 causes of evolution - ✔✔shrinking population, nonrandom mating, mutations,
migration, natural selection
✔✔Caffeine is a ___ - ✔✔Diuretic
Caffeine --> inhibit ADH production --> more urine
✔✔Parts of Nephron in order - ✔✔1) Bowman's Capsule
2) Proximal convoluted tubule
3) Loop of henle (descending, ascending) + vasa recta
4) Distal convoluted tubule
5) Collecting duct
✔✔aquaporins - ✔✔membrane proteins that allow water flow
✔✔How does ADH cause water retention? - ✔✔1) ADH/vasopressin binds to outer
receptors on principal cells —> causes mechanims which brings aquoporins to the
membrane of inner collecting duct
2) Water flows out of collecting duct because of a concentration gradient
*Interstitial fluid is hypertonic to urine !!
3) Water goes back to bloodstream through the vasa recta
**ADH acts on collecting duct AND distant convoluted tubule !!
✔✔hypertonic - ✔✔the more concentrated solution
✔✔hypotonic - ✔✔the less concentrated solution
✔✔How do the kidneys deal with hypertonic solution? - ✔✔1) thirst feeling
2) Water reabsorption from urine --> more concentrated urine
✔✔proteasome - ✔✔A giant protein complex that recognizes and destroys proteins
tagged for elimination by the small protein ubiquitin.
Destroys peptide bonds
✔✔Proteolysis - ✔✔decomposition of proteins by destroying peptide bonds
✔✔Proteases - ✔✔enzymes that catalyze proteolysis
✔✔Ubiquitin - ✔✔A protein that attaches itself to faulty or misfolded proteins and thus
targets them for destruction BY PROTEASOMES
✔✔Ubuiquinone - ✔✔Coenzyme Q
, a coenzyme that supports NAD+
✔✔Caspase - ✔✔A family of proteases that, when activated, mediates the destruction
of the cell BY APOPTOSIS
✔✔Kinase - ✔✔an enzyme that catalyzes the transfer of a phosphate group from ATP
to a specified molecule
enzyme that facilitates phosphorylation
✔✔conspecific - ✔✔members of the same species
✔✔probe (genetics) - ✔✔a complementary sequence of ssDNA or ssRNA that can
show when it binds
marked w/ radioactive or chemical tags
✔✔hybridize - ✔✔Two different nucleic acids uniting their complementary sites
✔✔microarray - ✔✔a grid of DNA segments of known sequence that is used to test and
map DNA fragments, antibodies, or proteins
tests how often a gene is expressed
✔✔temperate climate zone - ✔✔Cold winters and mild summers
Moderate rainfall
✔✔Drip tip leaves - ✔✔Leaves that allow water to drip down onto the ground to avoid it
being damaged by high amounts of rainfall.
✔✔sunken stomata - ✔✔reduces water loss as the water has to diffuse a long distance
before it reaches the outside of the leaf
✔✔Succulent leaves - ✔✔modified leaves for water storage
✔✔Dormant buds - ✔✔what most woody plants use to protect their growing tips during
the winter
suppression of growth
✔✔shallow roots - ✔✔take up water quickly after brief rainfall events
