DAT Booster Biology Practice Exam 2 Flashcards
All of the following are true regarding protein denaturation EXCEPT one. Which one is the EXCEPTION?
a. is a reversible process
b. can occur using strong bases
c. denaturing a protein changes its shape
d. can occur using radiation
e. part of the denatured proteins biological function is retained
e
a protein’s shape determines its
function
a protein’s shape determines its
loss of a protein’s configuration due to unfavorable environmental conditions, which results in the loss of the protein’s function.
Proteins can be denatured when they are removed from their
optimal temperature, pH range, or solvent.
Radiation and chemical damage can also lead to denaturation.
When proteins are denatured, all structural levels are lost besides the
primary structure
proteins loss in shape ultimately leads to a loss
in function
In most cases, denaturation is irreversible, but in some cases, if the proteins are returned to their optimal environmental conditions, denaturation can be
reversed and function is regained
The proteins can regain their native state when placed back in favorable environmental conditions. This process is known as renaturatio
One of the environmental conditions that cause denaturation is a pH that is either too high or too low. A strong base can create a very basic environment (high pH) which can lead to
the denaturation of a given protein.
Gastrulation describes the process by which three embryonic germ layers arise from the
primitive streak
The primitive streak is a structure formed by the
epiblast
three germ layers are listed from superficial to deep as follows:
ectoderm
mesoderm
endoderm.
Once these three germ layers are formed, the embryo is officially considered a
gastrula
The ectoderm will differentiate to form the
Nervous system (brain and spinal cord)
integument (epidermis, hair, epithelium of the nose, mouth, and anal canal)
sensory structures of the eyes, ears, and nose
the adrenal medulla.
Neural crest cells of the ectoderm will also form the teeth, jaws, and bones of the skull.
The mesoderm will give rise to the
musculoskeletal system
the circulatory system
the excretory system
the gonads
portions of the digestive and respiratory system
the notochord
the kidney
the dermis of the skin
the adrenal cortex.
endoderm will give rise to the
epithelial lining of the digestive and respiratory tract
portions of the liver
the pancreas
the gallbladder
the thyroid and parathyroid
the thymus
the lining of the urinary bladder.
Macromolecules result from the polymerization of
monomeric subunits
ex. proteins, polysaccharides, lipids, and nucleic acids.
DNA and RNA are the most common examples of nucleic acids and are responsible for
protein regulation
DNA and RNA are composed of
long strands of interconnected nucleotides.
Nucleotides are molecules consisting of a
pentose sugar, a phosphate group, and a nitrogenous base.
In order to polymerize, the 5’ phosphate group of one nucleotide and the 3’ hydroxyl group of a separate nucleotide undergo a
condensation (glycosidic) reaction.
condensation (glycosidic) reaction.
This creates a phosphodiester bond between adjacent nucleotides in a DNA or RNA strand.
phosphodiester bond
is what allows nucleotides to bond together in long chains.
Hydrogen bonds are bonds that occur between
hydrogen and oxygen, nitrogen, or fluorine.
In DNA, each nitrogenous base will hydrogen bond with the
nitrogenous base of its complementary nucleotide.
For example, adenine will hydrogen bond with thymine and guanine will hydrogen bond with cytosine. This is what creates the double strand that is seen within a DNA double helix.
Van der Waals forces are seen in
all compounds, including DNA.
Covalent bonding is the
sharing of electrons between two atoms.
Covalent bonding can be observed in the phosphodiester bonds of DNA and RNA.
bonds that exist within DNA is listed below:
hydrogen bonding
van der waals forces
phosphodiester bonds
covalent bonds
disulfide bonds occur in
tertiary structure of some proteins
these bonds occur between cysteines and aid in the structural integrity of proteins. Disulfide bonds are not seen in DNA.
Disulfide bonds are
covalent bonds
sarcomere
functional unit of a striated muscle fiber
the sarcomere is responsible for
muscle contraction
Sarcomeres are present in both
skeletal and cardiac muscle because both of these muscle types are striated.
Sarcomeres contain thick filaments:
myosin
Sarcomeres contain thin filaments:
actin
actin and myosin
slide past each other when muscle contracts
- sliding filament theory
individual myofilaments do not shorten in length, but rather, the sarcomere itself will
shorten in length as the myofilaments overlap one another
The Z-lines represent the
borders of 1 individual sacromere
The I-band is the region of the sarcomere that contains
thin filaments (actin)
The H-zone is the region of the sarcomere that contains
thick filaments (myosin)
The A zone is the area of the sarcomere where
actin and myosin overlap
The M-line represents the
middle of the sacromere
Which of the following layers covers the surface of cortical bone?
periosteum
Cortical bone is much denser than cancellous bone and is characterized by its presence of
osteons
Osteons are the functional unit of
cortical bone
At the center of each osteon is a structure known as the
Haversian canal.
The Haversian canal contains
nerves and blood vessels that supply bone cells with their required nutrients.
Cancellous bone, also known as spongy bone, is much more
flexible than cortical bone.
Instead of osteons, cancellous bone contains
trabeculae which contribute to strength and flexibility
red bone marrow which is the site of hemopoiesis (red blood cell development).
short bones are primarily made of
cancellous bones while long bones are primarily made of cortical bone.
short bones are primarily made of
cancellous bones while long bones are primarily made of cortical bone.
cortical bone (compact bone) creates the
outer layer of long bones with cancellous bone being housed within cortical bone at the metaphysis and epiphysis.
Cortical bone is composed of two fibrous membranes:
the periosteum and the endosteum
The periosteum is the
outermost membrane that wraps itself around cortical bone.
The endosteum is the innermost membrane of
cortical bone and is the border between cancellous and cortical bone.
Which one of the following phyla are deuterostomes?
echinodermata
All triploblastic organisms (organisms that possess all three germ layers) can be classified as either
protostomes or deuterostomes.
The terms ‘protostome’ and ‘deuterostome’ are used to describe certain processes that organisms undergo
during embryonic development.
Protostomes have
spiral cleavage
determinate cleavage
Determinate cleavage means that blastomeres are unable to
develop into a complete embryo if they are separated.
indeterminate cleavage
in which separated blastomeres ARE able to complete full development.
indeterminate cleavage
In protostomes, the blastopore (an opening created by the invagination of the primitive streak) will develop into the
mouth
Deuterostomes undergo
radial cleavage
indeterminate cleavage
In deuterostomes, the blastopore becomes
the anus
ex. humans
Platyhelminthes examples
(flukes, tapeworms, flatworms, planarians, and trematoda)
protosomes
most primitive triploblastic organisms.
They have only one opening to their digestive cavity which serves as both a mouth for ingesting food and an anus for excretion.
Cnidarians examples
hydra, jellyfish, coral, and sea anemones
neither protostomes nor deuterostomes.
This is because these organisms are diploblastic.
These organisms, similar to Platyhelminthes, have a gastrovascular cavity for their digestive system.
Nematodes examples
roundworms, ascarcis, trichina, C. elegans, and hookworms
protostomes
Nematodes are the most primitive organisms to possess an alimentary canal.
This means that Nematodes possess both a mouth and an anus in their digestive system.
Mollusks –
the phylum Mollusca (clams, squids, octopuses, snails, and slugs) are protostomes.
Mollusks are the most primitive organisms to possess an alimentary canal along with accessory organs, making a complete digestive system.
nucleolus
vital role in ribosome biogenesis
produces rRNA and assembles ribosomal subunits
Ribosomal subunits are made of
rRNA and proteins.
The proteins found in ribosomal subunits are shuttled into the
nucleoplasm via nuclear pores
Once in the nucleolus, rRNA and ribosomal proteins are integrated to create a
ribosomal subunit
Two ribosomal subunits comprise a
functional ribosome
Golgi apparatus is characterized by the presence of
cisternae which is the site of protein modification
operant conditioning
form of associate learning
organism learns a behavior with a reward or punishment
ex. offering a puppy a treat for going outside (positive reward)
The posterior pituitary is a gland made up of neuronal tissue that is continuous with the
hypothalamus
The posterior pituitary does not produce its own hormones, but rather, stores and secretes certain hormones that are made from the
hypothalamus
Examples of these hormones from posterior pituitary include
vasopressin (ADH)
oxytocin
vasopressin is an important hormone that
decreases urination.
This is important to counteract dehydration by increasing the reabsorption of water in the collecting duct of nephrons (recall that nephrons are the functional unit of the kidney).
This is done by increasing the number of aquaporins which are essentially water channels that accumulate on the collecting duct to allow for the movement of water back into the circulatory system. This will cause urine to become much more concentrated, the sole reason behind urine being yellow when we haven’t drunk enough water during the day.
Oxytocin
is released from the posterior pituitary.
Oxytocin is released during childbirth to increase the force of uterine contractions.
Oxytocin also stimulates the contraction of breast tissue to assist in milk ejection during breastfeeding.
Follicle-stimulating hormone (FSH) is released from the
anterior pituitary
FSH is responsible for the
production and growth of a follicle in females and the maturation of sperm in males
luteinizing hormone (LH)
released from anterior pituitary
responsible for the commencement of ovulation during menstrual cycle
responsible for the production of sperm in the seminiferous tubules in males
hGH
human growth hormone (somatotropin)
released from anterior pituitary
responsible for the growth and development of muscles and bones
cortisol is released from
adrenal cortex and adrenal glands
cortisol is a
glucocorticoid that accumulates during long term stress
Cortisol raises blood glucose levels by targeting
muscle cells, liver cells, and fat cells
The muscle provides
amino acids, the liver stores glycogen which can be converted to glucose via glycogenolysis, and the fat cells provide fatty acids that can be used for energy.
A man and a woman have normal skin color but both have one parent with albinism, which is caused by an autosomal recessive allele. If the couple intends on having 2 children, which of the following is the probability that both children will have albinism?
Therefore, there is a ¼ chance a child of this couple will have albinism (aa). Furthermore, the question states that the couple intends on having 2 children and asks for the probability of both children having albinism. Each child is an independent event, and so, we multiply the probability of the first child having albinism (¼) by the probability of the second child having albinism (¼). Therefore, ¼ x ¼ = 1/16 is the probability that both children will have albinism.
Down syndrome is a condition caused when nondisjunction occurs in meiosis I. Which of the following gametes would be produced from this condition?
Two gametes will lack chromosome #21 and two would have an extra copy
Which of the following produces and secretes a hormone responsible for decreasing blood calcium levels?
thyroid
Two glands in the endocrine system are responsible for regulating blood calcium levels:
parathyroid and thyroid
C-cells (also known as parafollicular cells) of the thyroid gland produce the hormone
calcitonin
which acts to decrease the calcium levels in the blood (think calcitonin = tone down)
Parathyroid Hormone (PTH) has the opposite effect as Calcitonin and is produced by the
chief cells of the parathyroid gland.
Calcitonin is released by the thyroid when blood calcium levels
high
In order to decrease blood calcium levels, calcitonin will stimulate osteoblasts to build more bone.
calcitonin will also inhibit osteoclast activity and proliferation. This prevents osteoclasts from breaking down bone and releasing calcium into circulation.
Adrenal cortex
the outer portion of an adrenal gland
produces and secretes:
1. mineralocorticoids, such as aldosterone which regulates blood pressure
2.glucocorticoids, such as cortisol which help regulate metabolism and the body’s response to stress and inflammation.
adrenal medulla
inner portion of an adrenal gland
produces catecholamines, specifically, adrenaline (epinephrine) and noradrenaline (norepinephrine) that are involved in the fight-or-flight response.
Anterior pituitary
The anterior pituitary produces and secretes several hormones, including Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Adrenocorticotropic Hormone (ACTH), etc…
The role of the collecting duct in the nephron of the kidney involves __________.
sodium reabsorption in response to aldosterone
to increase water and sodium reabsorption as well as potassium secretion in response to aldosterone and/or antidiuretic hormone/vasopressin.
Aldosterone is a
mineralocorticoid
released by adrenal gland ( cortex )
increases salt and water reabsorption while increasing potassium secretion in the distal convoluted tubule and collecting duct
The Hardy-Weinberg principle
states that populations are in genetic equilibrium if their allele frequencies do not change from generation to generation
used to determine allele frequencies within a population that is in genetic equilibrium
p + q = 1
p^2 + 2pq + q^2 = 1
p = frequency of the dominant allele
q= frequency of the recessive allele
p^2= frequency of homozygous dominant allele
2pq=frequency of heterozygous individuals
q^2= frequency of homozygous recessive individuals
In order for a population to be in Hardy-Weinberg equilibrium, the following conditions must be met:
- No Natural Selection
- No Mutations
- No gene flow (the population is isolated from others)
- Large populations (decreases the effect of genetic drift)
- Random Mating
What cells are the most abundant and the first to attack foreign infectious agents?
neutrophils
neutrophils
phagocytic cells that are part of the “innate immune response”.
the most abundant type of white blood cell and are generally the first to enter the infected tissues/organs to elicit an immune response.
followed by lymphocytes (specifically, natural killer cells), and then monocytes/macrophages.
Like neutrophils, monocytes are also phagocytes that work to
fight infections
monocytes can turn into
macrophages
which are very good at eating things, as well as presenting antigens to activate the adaptive immune response.
plasma cells and memory cells are part of the
adaptive immune response
derivatives of naive b cells
Once naive B cells are activated by a given antigen that is recognized, it begins proliferating into
plasma cells and memory cells.
Plasma cells function in the immediate
destruction of the invading pathogen while memory cells are “inactive”, where they lie dormant in circulation until they are activated by the same antigen upon subsequent infections.
Memory cells are useful in the occurrence that a pathogen returns, hence the name
memory cells
These cells will recognize a returning antigen and become activated. Once activated, they proliferate into plasma cells, which aid in a much faster and stronger immune response.
Helper T cells are derivatives of
naive T cells
which help mediate and assist in both the innate and adaptive immune response
Which of the following organisms is most abundant in a prairie biome?
grass
Temperate grasslands
fertile soil, its uneven seasonal rainfall, and seasonal droughts and fires.
Following fertilization, the zygote will begin a process known as
cleavage
Cleavage is the differentiation of the
zygote to form a ball of 8-16 cells (morula)
morula will continue to differentiate growing into a mass of 128 cells with a hollow center known as
blastocoel
blastula will differentiate into two structure form:
inner cell mass and trophoblast
when inner cell mass is formed, the embryo is now known as a
blastocyst
the inner cell mass will form two layers:
epiblast and hypoblast
what structure will begin the process of grastulation
primitive streak
Once the primitive streak has formed, the bilayer embryo will differentiate into
3 layers
fitness
measured by the # of fertile offspring an organism can produce that can reach reproductive age
yolk sac purpose in humans
first site of RBC synthesis
extraembryonic structure
allantois
urine acid storage in egg laying animals
becomes umbilical cord and urinary bladder in adults
intermediate filaments
found in cytoskeleton, cell junctions, and nuclear lamina
ex. keratin
Absolute refractory period
B
Time period in which a second action potential ABSOLUTELY cannot be initiated, no matter how large the applied stimulus is. The absolute refractory period is a result of inactive Na+ channels.
The absolute refractory period sets the upper limit for the frequency of action potentials. The absolute refractory period begins once the threshold potential is met and ends after repolarization (just before hyperpolarization begins).
Relative refractory period
C
is the time period immediately following the Absolute Refractory Period during which the initiation of a second action potential is possible, But a stronger-than-usual stimulus is required. The relative refractory period occurs when the membrane potential of the neuron is hyperpolarized (more negative than resting membrane potential). If the membrane potential of the neuron is more negative than the resting membrane potential, a stronger stimulus is required for the membrane potential to reach the threshold value and fire another action potential. During the relative refractory period, the voltage-gated Na+ channels are no longer activated
A defect in which structure of a plant would prevent an ovule from being produced?
pistil
flower-bearing plants.
angiosperms
ex fruits, maple, oaks, grass, etc.
The flower is the reproductive structure of an
angiosperm
the major structures of the flower include the
pistil
stamen
petals
pistil
female reproductive structure
3 parts of pistil
ovary: The ovary lies at the base of the style and is the site where ovules are produced. Ovules contain the female gamete of the plant which are fertilized by pollen to develop into a seed!
style: The style is the tube that leads from the stigma down to the ovary.
stigma: The stigma is the most superior structure and is the landing site for pollen.
stamen
male reproductive structure
anther and filament
anther: chamber where pollen develops
sepal
part of calyx of a flower that encases and protects the flower bud
may attract pollinators
petal
attracts pollinators
Polymerase chain reaction (PCR)
make millions of copies of a specified region of DNA.
utilizes DNA primers, Taq polymerase (a heat-resistant DNA polymerase), a thermal cycler, and a sample of the DNA that the researcher wishes to be amplified.
protocol for PCR requires the researcher to place the DNA sample, Taq polymerase, and DNA primers into a PCR tube
three stages of the polymerase chain reaction: denaturation (~95° C), primer annealing (~65° C), and elongation (~70° C). Each cycle of denaturation, primer annealing, and elongation, the amount of double-stranded DNA segments will double.
The blood type with the lowest chance of causing a transfusion reaction when donated is __________.
type O-
universal acceptor
AB+
bottleneck effect
whenever a population undergoes a dramatic decrease in size due to natural catastrophes or other events. A population bottleneck may be caused by a natural disaster, aggressive hunting practices, or habitat destruction. This results in a smaller population with a smaller gene pool, exaggerating the effect of genetic drift (the random increase or decrease in allele frequency).
Menstruation describes the sloughing off of the
uterine wall
causes the discharge of blood when an egg is not fertilized during that cycle
The menstrual cycle is a 28-day cycle with 3 distinct phases:
follicular phase (day 1-13)
ovulation (day 14)
luteal phase (day 15-28).
follicular phase
steady secretion of both luteinizing hormone and follicle stimulating hormone.
(FSH) stimulates the development of follicles in the ovary
one of these follicles (the Graafian follicle) will develop the most and this is where the egg (ovum) will be secreted from.
Nearing the end of the follicular phase, we see a rise in estrogen levels.
Estrogen will cause the innermost uterine lining (the endometrium) to thicken in preparation for the implantation of a developing embryo.
rise in estrogen also leads to a positive feedback loop, ultimately stimulating a sudden rise in luteinizing hormone (LH). This spike in LH is what triggers ovulation.
Ovulation phase:
quickest of the three phases and can simply be summarized as the release of an ovum from the Graafian follicle.
During this time, the egg exits the ovary and travels down the fallopian tube, approaching the uterus.
Fertilization of the egg typically occurs in the fallopian tube.
After the Graafian follicle has released the egg, it develops into the corpus luteum
luteal phase
Graafian follicle has released the egg, it develops into the corpus luteum.
corpus luteum will produce progesterone and some estrogen.
corpus luteum is being maintained by FSH and LH.
Progesterone, along with estrogen, will continue to thicken the endometrium in preparation for the implantation of a developing embryo.
If fertilization has not occurred, then the high levels of estrogen and progesterone will lead to negative feedback on the anterior pituitary, ultimately inhibiting the continued secretion of FSH and LH.
The drop in FSH and LH will lead to the degradation of the corpus luteum which leads to a decrease in estrogen and progesterone.
The decrease in estrogen and progesterone will ultimately lead to the sloughing off of the endometrium, the process known as menstruation.
modern cell theory
- All living organisms are composed of one or more cells
- Cell is the basic unit of structure, function, and organization in all organisms.
- All cells come from preexisting, living cells.
- Cells carry hereditary information.
As we can see, the Modern Cell Theory states that the cell is the basic unit of structure, function, and organization in all organisms.
Peptide bonds
are the bonds that exist between adjacent amino acids.
Peptide bonds are formed via dehydration synthesis, otherwise known as a condensation reaction
All amino acids are composed of an
alpha carbon, an amino group (NH2), hydrogen atom (H), and a carboxyl group (COOH).
The outer ear is made up of the
auricle/pinna
tympanic membrane
Sound travels through the external auditory canal before reaching
The tympanic membrane is a structure of the middle ear which vibrates the sounds and transfers those vibrations to 3 very small bones within the middle ear.
small bones in ear, ossicles
malleous
incus
stapes: connected to the oval window which bridges the gap between the middle ear and the inner ear.
Once the sound has reached the oval window, it gets transferred to the
cochlea
Within the cochlea is fluid and a basement membrane.
Hair cells detect the movement of the fluid and send different signals to the brain based on this movement via the auditory nerve. The inner ear also contains semicircular canals which assist with balance.
ciliary body
structure of the eye found behind the iris. The ciliary body contains the ciliary muscle which changes the shape of the lens in order to focus light on the retina.
What graphical representation shows the accumulation of biomass at each trophic level in an ecosystem?
ecological pyramid
The pancreas releases enzymes used in digestion. Which of the following pancreatic enzymes is used to cleave peptide chains?
chymotrypsin
As chyme enters the small intestine, cells of the small intestine will secrete
cholecystokinin, a hormone that, among other functions, will signal the pancreas to release its digestive enzymes.
Chymotrypsinogen and trypsinogen are secreted from the pancreas and converted into chymotrypsin and trypsin via enteropeptidase, which is an enzyme released from glands of the small intestine in response to the entrance of chyme.
