what is the crispr cas9 system used for in gene editing

ATI TEAS 7

TEAS Test 7 science quizlet

1. What is the primary function of the CRISPR-Cas9 system in gene editing?

A. To amplify specific DNA sequences.
B. To cut DNA at specific locations.
C. To deliver genes into cells.
D. To sequence entire genomes.

Correct answer: B

Rationale: The CRISPR-Cas9 system is a powerful tool used in gene editing to precisely target and cut DNA at specific locations within the genome. This system consists of a guide RNA that directs the Cas9 enzyme to the desired DNA sequence, where it creates a double-strand break. This break can then be repaired by the cell's natural DNA repair mechanisms, allowing for the introduction of specific genetic modifications. Options A, C, and D are incorrect as they do not accurately describe the primary function of the CRISPR-Cas9 system in gene editing. Amplifying DNA sequences, delivering genes into cells, and sequencing entire genomes are not the main functions of the CRISPR-Cas9 system, which is primarily focused on precise DNA cutting for targeted genetic modifications.

2. Anya was paid by Company X to analyze dwindling honeybee populations in the Southwest. After measuring hive populations over several months, she noticed no patterns in the geographic distributions of the deaths after comparisons with local maps of interest. This supported her hypothesis, so she took samples of the honey and the bees from the hives and performed dozens of dissections to confirm her suspicions. Which of the following is the most likely hypothesis upon which this research was performed?

A. Honeybees are being killed off, and their hives are destroyed by other extremely aggressive species of bees from the South.
B. Honeybees are contracting parasites in large droves.
C. Honeybees are so sensitive to certain pesticides that they die on contact.
D. Honeybees die in larger numbers around cell phone towers.

Correct answer: B

Rationale: The most likely hypothesis based on the information provided is that honeybees are contracting parasites in large droves. Anya observed no geographic patterns in hive deaths and proceeded to analyze honey and bees for further investigation. This suggests that she suspected a widespread issue affecting multiple hives simultaneously, consistent with a scenario where honeybees are being infected by parasites in high numbers, leading to dwindling populations across different locations. The other choices can be eliminated because there is no mention of aggressive species of bees from the South, no evidence pointing to pesticide sensitivity as the cause, and no indication of a correlation with cell phone towers in the information provided.

3. What is the name of the growth plates in children's bones where new bone tissue is formed?

A. Epiphyses
B. Diaphysis
C. Periosteum
D. Medullary cavity

Correct answer: A

Rationale: The correct answer is A: Epiphyses. Epiphyses are cartilaginous areas found at the ends of long bones, enabling growth and bone lengthening during childhood and adolescence. The diaphysis refers to the main shaft of a long bone. The periosteum is the outer bone layer responsible for nourishment and aiding in bone repair. The medullary cavity is the central cavity within the diaphysis that contains bone marrow but is not involved in new bone tissue formation.

4. What is involved in the involuntary reflex arc that withdraws your hand from a hot object?

A. Central nervous system only
B. Peripheral nervous system only
C. Both CNS and PNS
D. Sensory neurons only

Correct answer: C

Rationale: The involuntary reflex arc that withdraws your hand from a hot object involves both the central nervous system (CNS) and the peripheral nervous system (PNS). When your hand touches a hot object, sensory neurons in the PNS detect the heat and send signals to the spinal cord in the CNS. The spinal cord processes this information and sends a signal back through motor neurons in the PNS to move your hand away from the hot object. This coordinated response requires the collaboration of both the CNS and PNS to protect the body from harm. Choice A is incorrect because the reflex arc involves more than just the central nervous system. Choice B is incorrect because the reflex arc involves more than just the peripheral nervous system. Choice D is incorrect because the reflex arc also involves motor neurons, not just sensory neurons.

5. Which of the following is NOT a common location for lymph nodes?

A. Groin
B. Armpit
C. Neck
D. Liver

Correct answer: D

Rationale: The correct answer is 'D: Liver.' The liver is not a common location for lymph nodes. Lymph nodes are small, bean-shaped structures distributed throughout the body, including common sites like the groin, armpit, and neck. They play a crucial role in the immune system by filtering lymph fluid and trapping harmful substances, aiding the body in defending against infections and diseases. The liver, on the other hand, is an organ responsible for various functions like detoxification, metabolism, and storage, but it does not house lymph nodes.