the phrase survival of the fittest refers to

ATI TEAS 7

ati teas 7 science

1. What does the phrase 'survival of the fittest' refer to?

A. Organisms with the most complex anatomical structures are more likely to survive and reproduce.
B. Organisms that demonstrate the best adaptations to their environment have a higher chance of survival and reproduction.
C. All organisms have an equal probability of survival and reproductive success regardless of their traits.
D. Only the strongest and most aggressive individuals within a population will survive and reproduce.

Correct answer: B

Rationale: The phrase 'survival of the fittest' is often associated with the concept of natural selection, proposed by Charles Darwin. Natural selection is the process by which organisms best adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits to the next generation. This process does not necessarily favor the most complex anatomical structures (option A) or the strongest and most aggressive individuals (option D). Instead, it emphasizes the importance of adaptations that enhance an organism's ability to survive and reproduce in a specific environment. Option C is incorrect because natural selection results in differential reproductive success based on an organism's traits, meaning that not all organisms have an equal probability of survival and reproductive success.

2. At what stage is urine formed in the kidney?

A. After fluid reaches the bladder.
B. When fluid fills the collecting duct.
C. Before blood enters the glomerulus.
D. During fluid transport to the urethra.

Correct answer: B

Rationale: Urine is formed when fluid fills the collecting duct in the kidney. The collecting duct is where the final concentration of urine occurs after the filtration process in the nephron. Choice A is incorrect because urine formation happens before fluid reaches the bladder. Choice C is incorrect because urine formation occurs after blood has been filtered in the glomerulus. Choice D is incorrect because urine formation happens before fluid is transported to the urethra for elimination.

3. Which type of mutation involves a change in the number of chromosomes?

A. Point mutation
B. Frameshift mutation
C. Missense mutation
D. Aneuploidy

Correct answer: D

Rationale: A) Point mutation involves a change in a single nucleotide base pair within the DNA sequence. B) Frameshift mutation involves the insertion or deletion of nucleotides, causing a shift in the reading frame of the genetic code. C) Missense mutation involves a single nucleotide change that results in a codon that codes for a different amino acid. D) Aneuploidy involves a change in the number of chromosomes, where an individual may have an extra chromosome (trisomy) or a missing chromosome (monosomy). Aneuploidy can lead to genetic disorders such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X). Changing the number of chromosomes is a characteristic feature of aneuploidy, making it the correct answer. Point mutation, frameshift mutation, and missense mutation do not involve a change in the number of chromosomes and are focused on alterations at the nucleotide level within the DNA sequence.

4. Neurotransmitters send chemical messages across the gap between one neuron and another through which of the following structures?

A. Schwann cell
B. ganglion
C. synapse
D. axon

Correct answer: C

Rationale: Neurotransmitters send chemical messages across the gap between one neuron and another through a structure called the synapse. The synapse is a specialized junction where the axon of one neuron meets the dendrite or cell body of another neuron. Neurotransmitters are released from the axon terminal of the presynaptic neuron and travel across the synaptic cleft to bind to receptors on the postsynaptic neuron, transmitting the signal between the two neurons. Choice A, Schwann cell, is incorrect as Schwann cells are responsible for producing myelin sheath around axons in the peripheral nervous system, not for transmitting neurotransmitters between neurons. Choice B, ganglion, is incorrect as ganglia are clusters of nerve cell bodies outside the central nervous system and do not directly participate in the transmission of chemical messages between neurons. Choice D, axon, is incorrect as the axon is a long, slender projection of a neuron that conducts electrical impulses away from the cell body and towards the axon terminals, where neurotransmitters are released into the synapse, but it is not the structure across which neurotransmitters travel to communicate between neurons.

5. Which of the following structures can serve as a passageway for both food and air?

A. Esophagus
B. Laryngopharynx
C. Nasopharynx
D. Trachea

Correct answer: B

Rationale: The correct answer is the Laryngopharynx. It is a common passageway for both food and air. The Esophagus (Choice A) is solely for transporting food from the throat to the stomach. The Nasopharynx (Choice C) is primarily involved in the passage of air. The Trachea (Choice D) is responsible for conducting air to and from the lungs and does not play a role in the passage of food.