DAT Bootster Practice Biology Exam 4 Flashcards
In general, small and non-polar molecules such as oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) are permeable. In addition, small, uncharged, polar molecules are also permeable.
Any charged ions are not permeable to the cell membrane, regardless of size. Additionally, large and polar molecules like glucose are also not permeable to the cell membrane.
steroid hormones are lipophilic (lipid soluble), therefore, they are permeable. Examples of steroid hormones include cortisol, aldosterone, estrogen, testosterone, and progesterone.
Peptide hormones are hydrophilic (water-soluble) and therefore, are not permeable to the cell membrane. Examples of peptide hormones include insulin, glucagon, calcitonin, parathyroid hormone (PTH), prolactin, human growth hormone (HGH), thyroid stimulating hormone (TSH), luteinizing hormone (LH), etc.
Photosynthesis of plants can be broken down into two phases: the light-dependent reactions and the light-independent reactions. Which of the following occurs during the light-independent reactions of photosynthesis?
Fix CO2 into glucose
Photosynthesis
autotrophic process by which certain organisms utilize photons from the sun to convert carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and atmospheric oxygen (O2). The chemical equation for photosynthesis is shown below:
Photosynthesis can be broken down into two main phases:
the light-dependent reactions and the light-independent reactions (the Calvin cycle)
During the light-dependent reactions,
light energy is used to produce ATP and NADPH, both of which are directly used in the light-independent reactions. The light-independent reactions, also known as the Calvin cycle, is the second phase of photosynthesis.
The Calvin cycle involves the fixing of
6 CO2 molecules into 1 organic glucose molecule. The Calvin cycle can be broken down into 4 steps:
- Carboxylation: 6 CO2 + 6 RuBP join to form 12 PGA. This reaction is catalyzed by the enzyme rubisco, also known as RuBP carboxylase.
- Reduction: 12 ATP + 12 NADPH convert 12 PGA à 12 G3P, also known as PGAL. Energy is incorporated and the by-products NADP+ and ADP are used in the light-dependent reactions.
- Regeneration: 6 ATP convert 10 G3P à 6 RuBP. This regeneration of RuBP allows for the continuation of the Calvin cycle.
- Carbohydrate Synthesis: The two remaining G3P are used to synthesize glucose.
The overall chemical equation for the Calvin cycle is:
6CO2 + 18ATP + 12 NADPH à 18ADP + 18Pi + 12 NADP+ + 1 glucose
The promoter sequence is a sequence of nucleotides on a
DNA strand that RNA polymerase will bind to, just upstream of the gene being transcribed.
The promoter sequence is usually a sequence of
adenine (A) and thymine (T) nucleotides since adenine and thymine only bond to each other via 2 hydrogen bonds.
Both eukaryotes and prokaryotes possess
promoter regions.
Prokaryotic promoters are generally much more simple than eukaryotic promoters.
RNA polymerase is able to directly bind to prokaryotic promoters.
RNA polymerase is able to directly bind to prokaryotic promoters.
In eukaryotes, the promoter sequence is often more complex and larger than in eukaryotes. RNA polymerase in unable to directly bind to eukaryotic promoters and therefore, require the binding of transcription factors. Transcription factors will bind to promoters and can upregulate or downregulate transcription. One very common eukaryotic promoter sequence is known as the TATA box which will assist in positioning the RNA polymerase
Erythroblastosis fetalis is a hemolysis disease that can be fatal to the embryo. Which of the following conditions would cause this hemolysis disease?
Rh-negative blood from the mother interacts with Rh-positive blood from the baby
Which of the following is the correct taxonomic categorization for multicellular, sessile sponges?
Animalia
10 Phyla that belong to the Kingdom Animalia:
Porifera, Cnidaria, Platyhelminthes, Nematoda, Rotifera, Annelida, Molluska, Arthropoda, Echinodermata, and Chordata
There are currently 6 kingdoms that you’ll need to know for your test:
- Archaea
- Eubacteria
- Protista
- Fungi
- Plantae
- Animalia
Which of the following BEST describes microfilaments?
Made up of actin
Microfilaments, also known as
actin filaments, are 1 of the 3 components of the cytoskeleton in eukaryotic cells. The other 2 components are microtubules and intermediate filaments. Microfilaments are composed of a double helix of 2 actin (a globular protein) filaments. Microfilaments are crucial to cellular processes such as cytokinesis, intracellular transport, cell adhesions/junctions, and muscular contraction.
An active culture of fibroblasts is treated with radioactive deoxycytidine triphosphate and then the cells are lysed. Where would the radioactive carbon component be detected?
DNA
Because deuterostomes possess an enterocoelom, they are said to be
enterocoelous
What is a plasmid?
A circular piece of DNA
exist separately from the chromosomal DNA.
Plasmids can replicate independently within the host cell and can sometimes be transferred between bacterial cells via horizontal gene transfer (transformation, transduction, and conjugation)
the extracellular matrix (ECM) has three major components:
- Highly viscous proteoglycans, which cushion cells
- Insoluble collagen fibers, which provide strength and resilience
- Soluble multi-adhesive ECM proteins that bind proteoglycans and collagen fibers to receptors on the cell surface
Out of these components, collagen is the most prevalent. Collagen is a fibrous structural protein within the ECM that is produced from fibroblasts. Collagen assists in the binding of adjacent cells. It is also useful to know that every third amino acid that composes collagen is glycine.
Nucleotides are the building blocks for DNA. Which of the following are found in a nucleotide but NOT a nucleoside?
Phosphate group
Nucleosides are composed of
ribose sugar and a nitrogenous base.
Where does fertilization occur in humans?
fallopian tube and also known as uterine tube or oviduct,
The ovaries are the site of
oogenesis (egg production). Recall that ovulation is the stage of the female menstrual cycle where an ovum (egg) is released from the graafian follicle within the ovary. This egg will then travel down the fallopian tube where fertilization occurs. Fertilization occurs in the fallopian tube(s), not the ovary.
The seminiferous are the site of
of spermatogenesis (production of sperm) within the testes.
Which of the following describes the retina?
Contains photoreceptors known as rods and cones
Light will first enter the eye through the
cornea
Light will enter the cornea and then pass through a circular opening, known as the
pupil
After the pupil, the light will pass through a transparent, flexible structure known as the
lens
_______ will contract to change the shape of the lens so that the light will refract and focus onto the retina.
ciliary muscles
retina is filled with
photoreceptors, known as rods and cones, Rods will function at low levels of light and is responsible for night vision and black and white vision. Cones, on the other hand, are responsible for colored vision and visual acuity in bright light. These photoreceptors will generate electrical signals that converge in one spot in the back of the eye. The optic nerve will then carry these signals to the brain.
What occurs during the repolarization period of an action potential in neurons?
K+ channels open, leading to an efflux of K+ out of the cell
Once max value is reached, Na+ channels become inactivated while K+ ion channels open to allow for the efflux of K+ ions. This efflux of K+ restores polarization of the neuron; a process known as
repolarization
- However, the K+ channels are slow to close and therefore, too much K+ is released and the membrane potential stoops lower than -70mV, a process known as hyperpolarization. This period of time is brief and eventually, resting membrane potential is restored.
What does a sperm’s head contain?
sperm dna
If a scientist wanted to convert DNA into smaller fragments, which of the following enzymes would be used?
Endonuclease
Nucleases cleave phosphodiester bonds in the nucleic acid backbone. Based on their mode of action, two main classes have been defined:
- Exonuclease is an enzyme that cleaves nucleotides one at a time from the end of a polynucleotide chain.
- Endonucleases cleave nucleotides from inside of the polynucleotide chain
Protease –
Proteases are enzymes that cleave the peptide bonds between adjacent amino acids. Recall that amino acids are the monomeric subunit of proteins. When amino acids link together via peptide bonds, it makes a polypeptide chain. This polypeptide chain is the primary structure of a protein.
Lipase –
Lipase is an enzyme responsible for the breakdown of fats. Recall that chief cells of the stomach secrete gastric lipase and the pancreas secretes pancreatic lipase. Lipase is not responsible for the breakdown of nucleic acids.
DNA replication, DNA polymerase will add nucleotides in the
5’ à 3’ direction
The lagging strand is able to add nucleotides continuously as it is adding nucleotides in the direction of the replication fork (DNA polymerase will add nucleotides in the same direction that DNA is unwinding). This is not the case for the lagging strand, however, On the lagging strand, DNA polymerase is still adding nucleotides in the 5’ à 3’ direction, however, this direction points away from the replication fork. Because of this, DNA polymerase has to keep returning to the replication fork and add nucleotides in the opposite direction that DNA is unwinding. This creates small DNA fragments known as Okazaki fragments. Ligase is an enzyme that’s responsible for connecting these Okazaki fragments. Ligase is not responsible for cutting DNA into smaller fragments.
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Which of the following adaptations would be found in a small vertebrate with an efficient form of respiration?
gills
open circulatory systems utilize
hemolymph instead of blood as a medium for gas delivery. Closed circulatory systems, however, do rely on blood vessels that encapsulate blood and directly deliver gases to and from bodily tissues. Closed circulatory systems are much more efficient and are seen in organisms with greater oxygen demand, ultimately indicating a more efficient respiratory system.
Through what vessel does the liver secrete its products into the gut?
Common bile duct
There are two main ducts that directly extend from the liver that you need to know
the left and right hepatic ducts. The left and the right hepatic ducts will join to form the common hepatic duct.
cystic duct
extends from the gallbladder and joins the common hepatic duct to form the common bile duct.
The common bile duct will then empty its contents into the
small intestine. Because the common bile duct delivers the products produced from the liver into the small intestine (gut)
Sporophytes
diploid and possess structures known as sporangia. When sporangia undergo meiosis, they produce haploid spores. These haploid spores will undergo mitosis to become a multicellular gametophyte that is still haploid (recall the spores that underwent mitosis to produce the gametophyte are haploid).
The gametophyte is responsible for producing gametes which we should know are
haploid.
When two gametes fuse during fertilization, it produces a diploid zygote. This zygote will then undergo mitosis to become a multicellular diploid sporophyte. We’ve now finished the complete cycle!
(T/F) The sporophyte is the multicellular diploid stage and the gametophyte is the multicellular haploid stage
true
External intercostal muscles
inhalation
Internal intercostal muscles
forced exhalation.
Internal oblique muscles
The internal oblique muscles are located superficially on each side of the abdomen. The external obliques play a role in forced exhalation, not inspiration,
Which cellular process would be utilized to synthesize glucose if no carbohydrates were available?
Gluconeogenesis
Gluconeogenesis
creates new glucose molecules from non-carbohydrate substrates. One common example of gluconeogenesis is the Cori cycle.
under anaerobic conditions, facultative anaerobes will utilize
glycolysis and fermentation to continue to generate ATP in the absence of oxygen.
Humans undergo lactic acid fermentation which is the conversion of the
2 pyruvate into 2 lactate with the oxidation of 2 NADH into 2 NAD+ in the skeletal muscle. When oxygen becomes available again, that lactate will enter the liver to become a substrate of the Cori cycle.
The Cori cycle will
convert the lactate back into pyruvate within a hepatocyte (liver cell). That pyruvate can then be converted into glucose via gluconeogenesis. The liver will then release that glucose into the bloodstream, making it available for use by other tissues/organs. Pyruvate and lactate are not the only substrates that can be used for gluconeogenesis. Some additional substrates that can be used for gluconeogenesis include glycerol, oxaloacetate, and certain amino acids.
Glycogenolysis
Glycogen is the storage form of glucose, and it is stored in the liver and skeletal muscle. Glycogenolysis is the breakdown of glycogen in order to release usable glucose for the body. Glycogenolysis is a separate process from gluconeogenesis.
While studying the origins of humans, a study was conducted by comparing only maternal DNA. What DNA source would have been used for this type of study?
mitochondria
and Recall that the egg is much larger than the sperm. Therefore, during fertilization, the egg will not only contribute its nucleus, but also the majority of its cytoplasm.
Species A occupies the same niche as Species B
When two species occupy the same niche, those species are in competition for resources. For example, both lions and spotted hyenas occupy the same ecological niche in the African savanna. Both of these species are apex predators that compete for the same prey within their ecosystem. If there is a limited number of resources, the species that is more fit for their environment will ‘outcompete’ the other species which can lead to a decrease in the population size of the less fit species. When two species compete for a shared resource, it is commonly known as exploitation competition.
