B. Cancerous growth
Alzheimer's, Parkinson's, and Huntington's disease are neurodegenerative diseases, which are characterized by excessive apoptosis. Turner Syndrome is a genetic disease that does not have a direct connection to apoptosis. However, a lack of apoptosis would lead to cell proliferation, as the body would not be able to successfully eradicate damaged cells. This cell proliferation often manifests as cancer.
B. Cancerous growth
Cancer, and its resulting growths, is the result of uncontrolled cell proliferation. Apoptosis is programmed cell death, which functions both in normal cell development but is also a necessary part of destroying damaged and mutated cells that multiply uncontrollably. If apoptosis were to be deregulated, uncontrolled cell growths, including cancer, would be an expected result.
The Miller-Urey experiment was designed to test the "organic soup theory" originally put forward by Oparin & Haldane. Oparin and Haldane put forth the theory that the origin of the Earth's environment was a reducing environment (without O2), allowing for the formation of complex organic molecules from simpler ones. The energy for the synthesis of these molecules came from UV light, lightning, heat, and radiation present in the early atmosphere.
The experiment itself consisted of water (H2O, intended to imitate the early sea of the primitive Earth) in a flask that was heated to create water vapor. The water vapor then entered a flask containing methane (CH4), hydrogen gas (H2), and ammonia (NH3), intended to imitate the primitive Earth's atmosphere. Sparks were then created in this flask (to imitate lightning in the atmosphere), and the products created after being run through a condenser were collected and analyzed. Several organic compounds were found in the collected sample, including amino acids, hydrocarbons, formaldehyde, and hydrogen cyanide.
Coelomate Summary - The parazoa animals of the animal kingdom lack true tissues (those of the phylum Porifera), and the phylum Cnidaria are diploblast, having only two tissue types. Of the triploblast animals, there are three types: acoelomate (lack a true coelom), pseudocoelomate (have an internal cavity, but one that is not completely lined by mesoderm derived tissue), and coelomate (have a cavity lined by mesoderm derived tissue).
Pseudocoelomates: Nematodes, Rotifers
Coelomates: Annelids, Mollusks, Arthropods, Echinoderms, Chordates
C. Zona pellucida
The correct answer is [C]. Vitelline is a similar component in the egg cells of sea urchins, and is responsible for much of the same function. Progesterone plays a role in leading the sperm to the egg, but not in the binding. The zona pellucida is the outer layer of the egg that is responsible for the initial binding of the sperm to the egg. The ZP3 protein is responsible for the species-specific binding of the sperm to the egg, but is more important for helping galactosyltransferase (GaIT) activate the acrosome reaction. Without it, the sperm will not be able to bind to the egg. Once the egg has undergone the acrosome reaction and fused with the sperm, it can then bind to the uterine wall.
A. Vitelline membrane
Choosing the vitelline membrane is at first a tempting answer, as it is an oocyte component that functions in the binding of sperm. However, the vitelline membrane (or vitelline layer) is the term used to describe this structure in non-mammals (for example, a common model used to describe the process of egg fertilization is the sea urchin - the sea urchin egg would be said to have a surrounding vitelline membrane); therefore the answer choice is incorrect.
C. Zona pellucida
The zona pellucida (specifically the ZP3 protein) is the component of the oocyte responsible for the binding of sperm in mammalian fertilization, so the answer choice is correct. The zona pellucida is a glycoprotein membrane that surrounds the oocyte. It binds sperm, and is required to initiate the acrosome reaction (the sperm releases the contents of its acrosome as it approaches the egg which contributes to charge-based fast block of polyspermy). Other zona glycoproteins include ZP2, which helps in oocyte-sperm recognition and in the prevention of polyspermy, and ZP1, which cross-links ZP3 and ZP2. Without ZP1, the zona pellucida cannot form.
C. Posterior pituitary and adrenal cortex
The origin and effects of hormones is a common topic on the DAT. Here, we are looking for two structures that target the same organ with different hormones. The posterior pituitary releases ADH, which allows the kidneys to reabsorb more water. The adrenal cortex releases mineralocorticoids, such as aldosterone, which affects the kidney to increase salt reabsorption (which in turn increases water absorption as well due to changes in osmolarity).
The pancreas releases glucagon (increase blood glucose) from alpha cells and insulin (decrease blood glucose) from beta cells. The thyroid controls general metabolism and releases calcitonin, which lowers blood calcium. The parathyroid releases PTH (parathyroid hormone), which increases blood calcium. The anterior pituitary releases FSH, LH, ACTH, TSH, prolactin, and growth hormone. The testes produce testosterone.
The notochord consists of cells on the surface of the mesoderm germ layer, which provides support in lower chordates. It is considered the first "backbone" in chordates.
Germ layer Organ development
Ectoderm Epidermis of skin, hair, nails, neural tube, lens of eye, enamel of teeth
Mesoderm Dermis of skin, muscle, skeleton, circulatory system, gonads, kidneys, respiratory tracts, notochord
Endoderm Lining of digestive and layer of respiratory tracts, liver, pancreas
Process Reactants Products
Glycolysis (Cytosol) Glucose, ATP, NAD+, ADP ; ATP, NADH, pyruvate
Note: pyruvate is converted into acetyl CoA in a step before the Krebs cycle, releasing 1 NADH and 1 CO2.
Krebs Cycle (mitochondrial matrix) acetyl CoA, NAD+, FAD, ADP ; CO2, NADH, FADH2, ATP
Electron Transport Chain (mitochondrial cristae) O2, NADH, FADH2, ADP ; ATP, H2O, NAD+, FAD
Alcohol fermentation Pyruvate, NADH ; CO2, NAD+, ethanol
Lactic acid fermentation Pyruvate, NADH ; Lactate, NAD+
B. totipotent cell.
Two types of cleavage can occur. Indeterminate cleavage produces a blastomere that can individually complete normal development. This is how identical twins are born. Pluripotent cells cannot form an entire individual, but they can differentiate into any of the three primary germ layers (ectoderm, mesoderm, endoderm).
A totipotent cell can give rise to any and all human cells, and even an entire functional organism. Similarly, in indeterminate cleavage, if blastomeres are separated from the rest of the embryo, both will individually complete normal development. The product of an indeterminate cleavage can be thought of as a totipotent cell due to its ability to form a new organism, so the answer choice is correct.
C. pluripotent cell.
A pluripotent cell can give rise to all tissue types, but not an entirely new organism. In contrast, the product of indeterminate cleavage is able to fully complete development into a new organism; therefore the answer choice is incorrect. Once an embryo develops from a morula to a blastula, it loses its totipotency and becomes pluripotent.
E. multipotent cell.
A multipotent cell can give rise to a limited range of cells within a tissue type. In contrast, the product of indeterminate cleavage is able to fully complete development into a new organism; therefore the answer choice is incorrect. A multipotent stem cell that could give rise to new brain cells, for example, would be unable to differentiate to form new muscle cells (as these organs in embryonic origins and tissue type).