DAT Booster Biology Practice Exam 5 Flashcards
In contrast to a prokaryotic organism, which of the following is unique to eukaryotic gene expression?
A. Presence of a promoter region
B. Use of RNA polymerase
C. Polyadenylation of RNA
D. Presence of nucleotides
E. Simultaneous transcription and translation
C
Generally speaking, prokaryotes do not perform post-transcriptional modification, including the addition of a 5′ cap or a polyA tail to their RNA transcript. Furthermore, prokaryotes do not contain introns in their mRNA. Eukaryotic pre-mRNA must undergo several modifications before leaving the nucleus. To stabilize their mRNA, eukaryotes add a 5′ GTP cap and also perform polyadenylation to add a series of Adenine nucleotides to the end of the RNA transcript. Further, splicing is an mRNA processing event unique to eukaryotes and their subsequent gene expression. Splicing is a process in which the spliceosome removes introns from pre-mRNA and splices the exons, resulting in an mRNA that is ready to leave the nucleus – this process is visualized below.
do prokaryotes perform post-transcriptional modification
generally speaking, they do not.
prokaryotes do not contain
introns in their mRNA
eukaryotic pre-mRNA must undergo
several modifications before leaving the nucleus.
To stabilize their mRNA, eukaryotes add a
5’ GTP cap and perform polyadenylation
polyadenylation
add a series of adenine nucleotides to the end of RNA transcript
splicing
an mRNA processing event unique to eukaryotes and their gene expression
spliceosome removes introns from pre-mRNA and splices the exons, resulting in an mRNA that is ready to leave the nucleus
promoter region
eukaryotes and prokaryotes both have this for transcription
In prokaryotes = Pribnow box
In eukaryotes = TATA box
nucleotides are common to both
prokaryotes and eukaryotes as their form of genetic material.
simultaneous transcription and translation are a characteristic unique to
prokaryotes
LH stimulates
Leydig cells to produce testosterone. In turn, testosterone, but not LH directly, helps promote spermatogenesis.
estrogen is involved in the menstrual cycle and in the development of
secondary sex characteristics in females.
triiodothyronine (T3) is one of the thyroid hormones responsible for the
growth and neurological development in children and increasing basal metabolic rate.
FSH directly stimulates
Sertoli cells, facilitating spermatogenesis
stimulates the sertoli cells to promote the maturation of seminiferous tubules and spermatogenesis.
Blood is filtered in the glomerulus by
high hydrostatic pressure, which forces excess fluid and waste products into Bowman’s space.
Circulating blood enters the glomerulus through the
afferent arteriole and exits through the efferent arteriole.
juxtaglomerular cells in the kidney are located next to
the glomerulus (juxta = near/beside)
are derived from the smooth muscle cells of the afferent arteriole
When pressure is low in the afferent arteriole (due to a drop in blood pressure of the body), the juxtaglomerular cells respond by releasing
renin
Renin activates the renin-angiotensin-aldosterone system which restores
blood pressure through the mechanism as shown in the image below.
Without the activation of the renin-angiotensin-aldosterone system, it is more difficult for the body to
recover from a drop in blood pressure, and thus chronic hypotension may manifest.
kidney stones form as a result of
calcium and oxalate levels being high enough that they precipitate out of the filtrate, or urine, to form crystals known as kidney stones.
What molecule is regenerated during the Calvin Cycle?
RuBP
The Calvin cycle is the set of chemical reactions that take place during photosynthesis in
chloroplasts
Calvin cycle is a
This is a light-independent cycle as it takes place after the energy has been captured from sunlight during the light-dependent phase of photosynthesis.
The Calvin cycle consumes ATP and NADPH to produce
glyceraldehyde 3-phosphate (G3P) from CO2.
THREE turns of the Calvin cycle are required to produce a NET of
ONE molecule of G3P
only FIVE G3P are recycled to regenerate
THREE RuBP acceptor molecules.
SIX turns of the Calvin Cycle are required to produce
ONE molecule of glucose.
The Calvin cycle reactions can be divided into three main stages:
carbon fixation, reduction, and regeneration of RuBP (the CO2 receptor)
RuBP is also known as the
CO2 acceptor
plays a crucial role in the carbon fixation step of the Calvin cycle
The attachment of RuBP and CO2 catalyzed by the enzyme
rubisco ( RuBP carboxylase-oxygenase)
After three turns of the Calvin cycle,
6 molecules of G3P are produced;
5 of the 6 G3P molecules are used to regenerate 3 molecules of RuBP.
Commensalism
a relationship between living organisms of two species in which one species obtains benefits like locomotion, shelter, or support from the host species without either harming or benefiting it.
Mutualism –
a relationship in which both organisms benefit.
Parasitism
a relationship when one organism benefits but the other is harmed.
Which of the following events could lead to ecological succession in an already established ecosystem?
A. Newly formed sand dunes
B. Land formed from solidified lava
C. Deforestation
D. Seasonal change in sea levels
E. Permafrost
C
Option A. Newly formed sand dunes – This option is incorrect because newly formed sand dunes are pieces of land that did not exist before, making this an example of primary succession.
Option B. Land formed from solidified lava – This option is incorrect because land forming from lava would be classified as new land since the lava would not have existed there before. This is an example of primary succession.
Option D. Seasonal change in sea level – This option is incorrect because while seasonal changes in sea levels can alter the conditions of an ecosystem, they do not necessarily result in ecological succession unless they cause a significant disturbance or change to the existing community of species.
Option E. Permafrost – This option is incorrect because Permafrost is predominantly seen within tundra’s, and defines the frozen state of the ground that is seen majority of the year; therefore it can’t be considered a disturbance. It can support a small amount of vegetation.
Secondary succession
occurs when a natural habitat, that was previously occupied by vegetation and life, experiences a disturbance that eliminates all life forms, but then is able to become reoccupied by life/vegetation.
primary succession
occurs in essentially lifeless areas, such as regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier.
deforestation
deforestation can be followed by secondary succession as a pre-existing forest would experience a disturbance that would eliminate many sources of food and vegetation, and thus would eliminate many forms of life.
systemic circuit
distributes oxygenated blood containing nutrients to all body tissues via arteries, which carry blood away from the heart. These arteries leave from the left ventricle, as shown in the image below. When oxygenated blood reaches the capillaries within the systemic tissues, it delivers O2 and nutrients to the tissues and picks up CO2. Veins then return the deoxygenated blood back to the heart so that it can enter the pulmonary circuit
pulmonary circuit
pumps deoxygenated blood through the pulmonary arteries to capillaries in the lungs to facilitate gas exchange. The pulmonary arteries leave from the right ventricle, as shown in the image below. The capillaries are in close contact with lung alveoli, where the blood becomes reoxygenated. The pulmonary veins then return the oxygenated blood to the heart so that it can be pumped through the systemic circuit.
blood moving to lungs order:
When the blood picks up oxygen in the lungs, it then flows from the lungs in this direction:
Which of the following sphincters, if damaged, would disrupt the passage of digested material between small and large intestine?
ileocecal
ileocecal sphincter
is a sphincter muscle valve separating the small and large intestine.
The ileum
the longest part of the small intestine
joins the cecum, the first portion of the large intestine, at the ileocecal sphincter.
cardiac sphincter
also known as the esophageal sphincter
allows food to pass from the esophagus into the stomach.
Pyloric sphincter
pyloric sphincter allows chyme to pass from the stomach into the small intestine.
Esophageal sphincter
esophageal sphincter, also known as the cardiac sphincter, allows food to pass from the esophagus into the stomach.
Rectal sphincter
the rectal, or anal, sphincter, allows stool to pass through the rectum out of the anus.
Peroxisomes are membrane-bound organelles that are found in the cytoplasm of
eukaryotic cells
They play a key role in the oxidation of specific biomolecules.
peroxisomes
a major function of peroxisomes is
a major function is the breakdown of fatty acids through beta-oxidation.
H2O2is toxic, however, another peroxisomal enzyme, called _________ uses this H2O2 to oxidize other substrates.
catalase
Lysosomes
lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself.
The majority of coelomate invertebrates develop as protostomes in which the oral (mouth) end of the animal develops from the
first developmental opening, the blastopore.
In deuterostomes,
the blastopore becomes the anus; the oral end of the animal develops from the second opening. Examples of deuterostomes include echinoderms and chordates. Below is an illustration to help visualize this concep
Pepsinogen is secreted by
chief cells in the mucosal layer of the stomach
Once it is secreted into the stomach lumen, the hydrochloric acid causes it to cleave itself into its active form pepsin.
Pepsinogen is produced instead of pepsin because pepsin is a
very strong endopeptidase
if chief cells secreted pepsin, the mucosal layer would be damaged as the pepsin moved along the lumen.
Since pepsinogen is a zymogen, it is inactive and cannot catalyze any reactions; in other words, it must be activated before it can perform enzymatic functions.
statrum corneum
is composed of 20–30 layers of these dead keratin-filled cells and functions as a physical barrier to protect the organism against pathogens, ultraviolet light, water loss, and injury.
stratum granulosum
lamellar granules
stratum spinosum
langerhan cells
keratinocyte
stratum basale
Divergent evolution
occurs due to an accumulation of differences between closely related species populations, leading to speciation.
Therefore, they become a different species to their ancestors and what was once one species has diverged into two.
Pterophyta (ferns) are
vascular plants
alternate between haploid and diploid forms
reproduce via spores
have neither seeds or flowers
vascular
sporophyte is dominant phase
Fertilization of the secondary oocyte by the sperm occurs, after which the secondary oocyte completes
meiosis II resulting in a fertilized mature ovum.
Which of the following describes the process of a group of cells directing the development of another group of cells?
induction
process of cells influencing the development of other cells, specifically during differentiation. This is usually carried out using a cell-signaling cascade using signaling vectors such as growth factors. The image below illustrates this phenomenon.
In humans when a female is born, the development of her oocyte is arrested in which of the following stage?
prophase 1 of meiosis
