USABO EXAM Review QUESTIONS
WITH CORRECT SOLUTIONS||100%
GUARANTEED PASS|| A+
GRADED||UPDATED 2025/2026
SYLLABUS||<<NEWEST VERSION>>
Phylum Nematoda - ANSWER ✓ Animal Kingdom
roundworms, trhee cell layers including a mesoderm
has pseudocoelom
pseudocoelom - ANSWER ✓ Phylum Nematoda
a body cavity that partially lines the interior (mesoderm) body wall but not around
the gut (endoderm)
hydrostatic skeleton - ANSWER ✓ in phylum annelida
coelom filled with water that allow for complex movement
Phylum Arthropoda - ANSWER ✓ joint appendages
open circulatory system
no hemoglobin in blood
exoskeletons made of chitin
spiracles and tracheal tubes for respiration
Class: Insecta - ANSWER ✓ Phylum Athropoda
winged, has three pairs of legs, spiracles, and tracheal tubes for breathing
Class: Arachnid - ANSWER ✓ Phylum Arthropodaspinds, have four pairs of legs
and "book lungs)
crustaceans - ANSWER ✓ segmented bodies with variable appendages
some have gills
-lobsters, crawfish
, Phylum Mollusca - ANSWER ✓ clams, squid, snail
body shapes differ, similar with
-muscular foot
-mantle that secretes a shell
-radula
mostly aquatic with gills
Phylum Echinodermata - ANSWER ✓ Animal Kingdom
echinoderm - radially symmetrical marine invertebrates including e.g. starfish and
sea urchins and sea cucumbers
anchor to surfaces with tube feet
deauterostomes
Phylum Chordata - ANSWER ✓ Animal Kingdom
has notochord
contains subphylum: vertebrates
notochord - ANSWER ✓ a flexible rodlike structure that forms the supporting axis
of the body in the lowest chordates and lowest vertebrates and in embryos of
higher vertebrates
vertebrates - ANSWER ✓ includes fish, reptiles, birds, and mammals
notochord always present at least in embryonic stage
usually have bony or cartilaginous endoskeletons
chambered hearts for circulation
allows for more complex nervous system
amphibians - ANSWER ✓ vertebrate
live close to water
have simple lungs or gills
lays soft eggs
reptiles - ANSWER ✓ vertebrate
have hard-shelled eggs
have thicker, dry skin for land mobility
birds - ANSWER ✓ vertebrate
evolved from reptilian dinosaurs
,four-chambered heart to allow for flying
hard-shelled egg
archaeopteryx
mammals - ANSWER ✓ vertebrate
hair, sweat gland, mammary gland, four-chambered hearts
good at regulating body-temp
monotremes - ANSWER ✓ mammals that lay eggs
marsupials - ANSWER ✓ mammals that have a pouch in which use for a majority
of their young's development
placental - ANSWER ✓ gestate young to a more mature state {than marsupials},
provide nutrition and gas exchange
primates - ANSWER ✓ vertebrates-mammals
have opposable thumbs and stereoscopic vision for depth perception
binary fission - ANSWER ✓ what prokaryotes use to reproduce
the process of , a form of asexual reproduction in single-celled organisms by which
one cell divides into two cells of the same size
mitosis - ANSWER ✓ the process in which eukarytoic cells divide to make two
daughter cells with the same genomic complement as the parent
highly regulated
meiosis - ANSWER ✓ specialized form of division involved in sexual
reproduction that makes male and female gametes (single copy of genome)
conjugation - ANSWER ✓ used by bacteria to move genes between cells by
exchanging circular extra-chormosomal DNA, used in Binary Fission
S stage of Interphase - ANSWER ✓ Mitosis
DNA synthesis takes place, each chromosome is replicated so that each daughter
cell has one complete copy
, centromere - ANSWER ✓ center of wound up DNA that holds together
chromatics
telomere - ANSWER ✓ end of chromatid
Prophase - ANSWER ✓ dark solid bands form- condensed chromosomes
centrioles make the spindle apparatus and the nucleic membrane dissolves
Metaphase - ANSWER ✓ spindle fully elongates where the nucleus once was
Kinetochore fibers attach to chromosomes at metaphase plate and they line up
Kinetochore - ANSWER ✓ where the chromosomes attach to the spindle
apparatus during Mitosis
Anaphase - ANSWER ✓ sister chromatids are pulled apart by a kinetochore and
spindle fibers
each daughter has one of each chromosome
Telophase - ANSWER ✓ spindle apparatus disappears
nuclear membrane reforms around each set of chromosomes
nucleoli reappear
chromosomes uncoil
Cytokinesis - ANSWER ✓ actual division of cells after DNA has been divided by
mitosis
cytoplasm and all organelles of cell are divided
budding - ANSWER ✓ parent cells make daughter cells with less cytoplasm, but
same amount of DNA
parthenogensis - ANSWER ✓ when the egg develops int he absence of
fertilization through mitotic cell division
regeneration - ANSWER ✓ the ability of certain animals to grow back missing
body parts, and sometimes whole organisms
haploid - ANSWER ✓ sex cells that are made in meiosis in males and females,
have single copy of genome
WITH CORRECT SOLUTIONS||100%
GUARANTEED PASS|| A+
GRADED||UPDATED 2025/2026
SYLLABUS||<<NEWEST VERSION>>
Phylum Nematoda - ANSWER ✓ Animal Kingdom
roundworms, trhee cell layers including a mesoderm
has pseudocoelom
pseudocoelom - ANSWER ✓ Phylum Nematoda
a body cavity that partially lines the interior (mesoderm) body wall but not around
the gut (endoderm)
hydrostatic skeleton - ANSWER ✓ in phylum annelida
coelom filled with water that allow for complex movement
Phylum Arthropoda - ANSWER ✓ joint appendages
open circulatory system
no hemoglobin in blood
exoskeletons made of chitin
spiracles and tracheal tubes for respiration
Class: Insecta - ANSWER ✓ Phylum Athropoda
winged, has three pairs of legs, spiracles, and tracheal tubes for breathing
Class: Arachnid - ANSWER ✓ Phylum Arthropodaspinds, have four pairs of legs
and "book lungs)
crustaceans - ANSWER ✓ segmented bodies with variable appendages
some have gills
-lobsters, crawfish
, Phylum Mollusca - ANSWER ✓ clams, squid, snail
body shapes differ, similar with
-muscular foot
-mantle that secretes a shell
-radula
mostly aquatic with gills
Phylum Echinodermata - ANSWER ✓ Animal Kingdom
echinoderm - radially symmetrical marine invertebrates including e.g. starfish and
sea urchins and sea cucumbers
anchor to surfaces with tube feet
deauterostomes
Phylum Chordata - ANSWER ✓ Animal Kingdom
has notochord
contains subphylum: vertebrates
notochord - ANSWER ✓ a flexible rodlike structure that forms the supporting axis
of the body in the lowest chordates and lowest vertebrates and in embryos of
higher vertebrates
vertebrates - ANSWER ✓ includes fish, reptiles, birds, and mammals
notochord always present at least in embryonic stage
usually have bony or cartilaginous endoskeletons
chambered hearts for circulation
allows for more complex nervous system
amphibians - ANSWER ✓ vertebrate
live close to water
have simple lungs or gills
lays soft eggs
reptiles - ANSWER ✓ vertebrate
have hard-shelled eggs
have thicker, dry skin for land mobility
birds - ANSWER ✓ vertebrate
evolved from reptilian dinosaurs
,four-chambered heart to allow for flying
hard-shelled egg
archaeopteryx
mammals - ANSWER ✓ vertebrate
hair, sweat gland, mammary gland, four-chambered hearts
good at regulating body-temp
monotremes - ANSWER ✓ mammals that lay eggs
marsupials - ANSWER ✓ mammals that have a pouch in which use for a majority
of their young's development
placental - ANSWER ✓ gestate young to a more mature state {than marsupials},
provide nutrition and gas exchange
primates - ANSWER ✓ vertebrates-mammals
have opposable thumbs and stereoscopic vision for depth perception
binary fission - ANSWER ✓ what prokaryotes use to reproduce
the process of , a form of asexual reproduction in single-celled organisms by which
one cell divides into two cells of the same size
mitosis - ANSWER ✓ the process in which eukarytoic cells divide to make two
daughter cells with the same genomic complement as the parent
highly regulated
meiosis - ANSWER ✓ specialized form of division involved in sexual
reproduction that makes male and female gametes (single copy of genome)
conjugation - ANSWER ✓ used by bacteria to move genes between cells by
exchanging circular extra-chormosomal DNA, used in Binary Fission
S stage of Interphase - ANSWER ✓ Mitosis
DNA synthesis takes place, each chromosome is replicated so that each daughter
cell has one complete copy
, centromere - ANSWER ✓ center of wound up DNA that holds together
chromatics
telomere - ANSWER ✓ end of chromatid
Prophase - ANSWER ✓ dark solid bands form- condensed chromosomes
centrioles make the spindle apparatus and the nucleic membrane dissolves
Metaphase - ANSWER ✓ spindle fully elongates where the nucleus once was
Kinetochore fibers attach to chromosomes at metaphase plate and they line up
Kinetochore - ANSWER ✓ where the chromosomes attach to the spindle
apparatus during Mitosis
Anaphase - ANSWER ✓ sister chromatids are pulled apart by a kinetochore and
spindle fibers
each daughter has one of each chromosome
Telophase - ANSWER ✓ spindle apparatus disappears
nuclear membrane reforms around each set of chromosomes
nucleoli reappear
chromosomes uncoil
Cytokinesis - ANSWER ✓ actual division of cells after DNA has been divided by
mitosis
cytoplasm and all organelles of cell are divided
budding - ANSWER ✓ parent cells make daughter cells with less cytoplasm, but
same amount of DNA
parthenogensis - ANSWER ✓ when the egg develops int he absence of
fertilization through mitotic cell division
regeneration - ANSWER ✓ the ability of certain animals to grow back missing
body parts, and sometimes whole organisms
haploid - ANSWER ✓ sex cells that are made in meiosis in males and females,
have single copy of genome
