Which tissue within a leaf has the most chloroplasts?

A) xylem
B) phloem
C) epidermis
D) spongy mesophyll
E) palisade mesophyll

Which substance is a reactant in the following chemical equation? CO₂ + H₂O ↔ H₂CO₃

A) water
B) carbon
C) oxygen
D) hydrogen
E) carbonic acid

Ammonia, a nitrogen containing-waste compound found in the blood, is a waste product of ____ breakdown.

A) carbohydrate
B) protein
C) lipid
D) mineral
E) vitamin

Sarah comes home from school with a horrible pressure behind her eyes. Her nose is running and she has a headache. She recently had a cold. What is Sarah most likely suffering from?

A) otitis media
B) sinusitis
C) bronchitis
D) asthma
E) pneumonia

The persistence of malaria and sickle-cell anemia within a population best illustrates ____.

A) bottlenecking
B) balanced polymorphism only
C) natural selection only
D) artificial selection only
E) balanced polymorphism and natural selection

Crossing over is one of the most important events in meiosis because ____.

A) it produces new combinations of alleles on chromosomes
B) homologous chromosomes must be separated into different daughter cells
C) the number of chromosomes allotted to each daughter cell must be halved
D) homologous chromatids must be separated into different daughter cells
E) it decreases genetic diversity

What is the correct order of events in muscle contraction?

A) action potential → synaptic cleft → sarcoplasmic reticulum → sarcolemma → calcium ions bind to troponin
B) action potential → synaptic cleft → sarcolemma → sarcoplasmic reticulum → calcium ions bind to troponin
C) action potential → sarcoplasmic reticulum → synaptic cleft → sarcolemma → calcium ions bind to troponin
D) action potential→ sarcolemma → sarcoplasmic reticulum → synaptic cleft → calcium ions bind to troponin
E) action potential → sarcolemma → synaptic cleft → sarcoplasmic reticulum → calcium ions bind to troponin

From months 5 to 7, a fetus is covered in a fine down called

A) chorion.
B) fuzz.
C) lanugo.
D) vernosa.
E) hairs.

Which type of neural circuit is best for producing a prolonged output?

A) A converging circuit
B) A diverging circuit
C) A reverberating circuit
D) A presynaptic pool
E) An autonomic pool

Dr. Clark has developed a new treatment that stimulates the innate immunity to be more sensitive to cancer cells. Which of the following cells would most likely be stimulated by this new drug?

A) NK cells
B) B lymphocytes
C) Cytotoxic T cells
D) Interferons