USABO 2025 Mass Deck Latest Update 2025-
2026 Exam 450 Questions with 100% Verified
Correct Answers Guaranteed A+
2 functions of eye muscles - CORRECT ANSWER: Detect light intensity & adjust(Iris
opens/closes based on light level)
Near vs. far vision (Ciliary body makes the lens more flat or bowl-like)
3' side has - CORRECT ANSWER: 3rd carbon on the 5 carbon sugar
4 parts of an operon - CORRECT ANSWER: PROG
promoter (DNA sequence)
repressor (blocking protein)
operator (DNA sequence)
gene (DNA sequence)
43S PIC (pre-initiation complex) - CORRECT ANSWER: Part of 40S ribosome subunit
that binds to eukarytoic mRNA (from the 5' cap)
5 causes of evolution - CORRECT ANSWER: shrinking population, nonrandom mating,
mutations, migration, natural selection
5' side has - CORRECT ANSWER: a phosphate group
a-ketoglutarate dehydrogenase - CORRECT ANSWER: a-ketoglutarate --> succinyl-
CoA
Reduces NAD+ to NADH
,Releases co2
Aconitase - CORRECT ANSWER: citrate --> isocitrate
ACTH (Adrenocorticotrophic hormone) - CORRECT ANSWER: Stimulates
glucocorticoid secretion by adrenal cortex- (Produced in Pituitary Gland)
ACTH / Adrenocorticotropic hormone - CORRECT ANSWER: Secreted by pituitary
gland
Peptide hormone
Facilitates CORTISOL production —> negative feedback loop
ADH (Antidiuretic hormone) - CORRECT ANSWER: Conserves water by decreasing
urine and sweating and by increasing blood pressure by constricting arteries (Produced
in Hypothalmus & Pituitary glands)
Adrenal Glands - CORRECT ANSWER: Paired pyramid shaped glands located on the
superior to kidney bilatteraly - The outer layer, cortex, produces 3 types of hormones
Mineralocorticoids, Glucocorticoids, Androgens
The inner layer, medulla, produces 2 hormones
Epinephrine and Norepinephrine
agarose gel - CORRECT ANSWER: gel matrix used for DNA electrophoresis; big pores
Albumin function - CORRECT ANSWER: transport nonpolar substances
maintain osmotic pressure
Allantois - CORRECT ANSWER: Begin as extensions of endoderm
,Surrounded by mesoderm cells
Allantois - CORRECT ANSWER: Forms part of umbilical cord and part of urinary
bladder
Allantois - CORRECT ANSWER: stores wastes & medaites gas exchange
allopatric speciation - CORRECT ANSWER: geographic barrier forms —> 2 populations
isolated —> 2 populations diverge into different species
alternation of generations - CORRECT ANSWER: A life cycle in which there is both a
multicellular diploid form, the sporophyte, and a multicellular haploid form, the
gametophyte
characteristic of ALL plants and some algae.
Amino-acid derived hormones: - CORRECT ANSWER: - Name ends w/ "-ine"
- VERY small hormones
- Made from tyrosine (Tyr) and tryptophan (Trp)
- Polar —> water soluble
Amnion - CORRECT ANSWER: Forms inner sac around embryo, holds the amniotic
fluid in which embryo floats
amnion - CORRECT ANSWER: Innermost membranous sac surrounding the developing
fetus
amniotic sac and fluid
Amphipathic - CORRECT ANSWER: having both a hydrophilic region and a
hydrophobic region
, polar & nonpolar end
amylase - CORRECT ANSWER: Enzyme in saliva that breaks the chemical bonds in
starches
Androecium - CORRECT ANSWER: stamen
Androgens - CORRECT ANSWER: Increase growth of axillary and pubic hair
F - contribute to libido and source of estrogens after menopause (Produced in Adrenal
Glands)
anode - CORRECT ANSWER: Positive electrode
Anterior Pituitary Gland - CORRECT ANSWER: Produced Hormones:
1. Follicle-stimulating hormone (FSH)
2. Leteinizing hormone (LH)
3. Adrenocorticotrophic hormone (ACTH)
4. Thyroid-stimulating hormone (TSH)
5. Prolactin
6. Endorphins
7. Human growth hormone (HGH)
Anther - CORRECT ANSWER: tip of stamen where pollen is produced (via
microgametogenesis)
Antheridium - CORRECT ANSWER: male sex organ of nonflowering plants (all non-
angiosperms)
2026 Exam 450 Questions with 100% Verified
Correct Answers Guaranteed A+
2 functions of eye muscles - CORRECT ANSWER: Detect light intensity & adjust(Iris
opens/closes based on light level)
Near vs. far vision (Ciliary body makes the lens more flat or bowl-like)
3' side has - CORRECT ANSWER: 3rd carbon on the 5 carbon sugar
4 parts of an operon - CORRECT ANSWER: PROG
promoter (DNA sequence)
repressor (blocking protein)
operator (DNA sequence)
gene (DNA sequence)
43S PIC (pre-initiation complex) - CORRECT ANSWER: Part of 40S ribosome subunit
that binds to eukarytoic mRNA (from the 5' cap)
5 causes of evolution - CORRECT ANSWER: shrinking population, nonrandom mating,
mutations, migration, natural selection
5' side has - CORRECT ANSWER: a phosphate group
a-ketoglutarate dehydrogenase - CORRECT ANSWER: a-ketoglutarate --> succinyl-
CoA
Reduces NAD+ to NADH
,Releases co2
Aconitase - CORRECT ANSWER: citrate --> isocitrate
ACTH (Adrenocorticotrophic hormone) - CORRECT ANSWER: Stimulates
glucocorticoid secretion by adrenal cortex- (Produced in Pituitary Gland)
ACTH / Adrenocorticotropic hormone - CORRECT ANSWER: Secreted by pituitary
gland
Peptide hormone
Facilitates CORTISOL production —> negative feedback loop
ADH (Antidiuretic hormone) - CORRECT ANSWER: Conserves water by decreasing
urine and sweating and by increasing blood pressure by constricting arteries (Produced
in Hypothalmus & Pituitary glands)
Adrenal Glands - CORRECT ANSWER: Paired pyramid shaped glands located on the
superior to kidney bilatteraly - The outer layer, cortex, produces 3 types of hormones
Mineralocorticoids, Glucocorticoids, Androgens
The inner layer, medulla, produces 2 hormones
Epinephrine and Norepinephrine
agarose gel - CORRECT ANSWER: gel matrix used for DNA electrophoresis; big pores
Albumin function - CORRECT ANSWER: transport nonpolar substances
maintain osmotic pressure
Allantois - CORRECT ANSWER: Begin as extensions of endoderm
,Surrounded by mesoderm cells
Allantois - CORRECT ANSWER: Forms part of umbilical cord and part of urinary
bladder
Allantois - CORRECT ANSWER: stores wastes & medaites gas exchange
allopatric speciation - CORRECT ANSWER: geographic barrier forms —> 2 populations
isolated —> 2 populations diverge into different species
alternation of generations - CORRECT ANSWER: A life cycle in which there is both a
multicellular diploid form, the sporophyte, and a multicellular haploid form, the
gametophyte
characteristic of ALL plants and some algae.
Amino-acid derived hormones: - CORRECT ANSWER: - Name ends w/ "-ine"
- VERY small hormones
- Made from tyrosine (Tyr) and tryptophan (Trp)
- Polar —> water soluble
Amnion - CORRECT ANSWER: Forms inner sac around embryo, holds the amniotic
fluid in which embryo floats
amnion - CORRECT ANSWER: Innermost membranous sac surrounding the developing
fetus
amniotic sac and fluid
Amphipathic - CORRECT ANSWER: having both a hydrophilic region and a
hydrophobic region
, polar & nonpolar end
amylase - CORRECT ANSWER: Enzyme in saliva that breaks the chemical bonds in
starches
Androecium - CORRECT ANSWER: stamen
Androgens - CORRECT ANSWER: Increase growth of axillary and pubic hair
F - contribute to libido and source of estrogens after menopause (Produced in Adrenal
Glands)
anode - CORRECT ANSWER: Positive electrode
Anterior Pituitary Gland - CORRECT ANSWER: Produced Hormones:
1. Follicle-stimulating hormone (FSH)
2. Leteinizing hormone (LH)
3. Adrenocorticotrophic hormone (ACTH)
4. Thyroid-stimulating hormone (TSH)
5. Prolactin
6. Endorphins
7. Human growth hormone (HGH)
Anther - CORRECT ANSWER: tip of stamen where pollen is produced (via
microgametogenesis)
Antheridium - CORRECT ANSWER: male sex organ of nonflowering plants (all non-
angiosperms)
