Four Types of Sentences ; 2) compound; 3) complex; and ; participial phrases used as adjectives, etc.) ; the first example creates suspense.) ; otherwise, she would have no money to buy presents for herself at Christmas time. ; his wife Joan works in a perfume factory nearby. 1 ; or ; they are not moveable. ; for example, adverb clauses can often appear either at the beginning or the end of a sentence. ; they must be connected to a simple sentence. (Clauses which cannot stand alone are called subordinate or dependent clauses.)
"the most widely used psychoactive substance on Earth ."
Synder, Daly and Bruns have recently proposed that
caffeine affects behavior by countering the activity in
(5) the human brain of a naturally occurring chemical called
adenosine. Adenosine normally depresses neuron firing
in many areas of the brain. It apparently does this by
inhibiting the release of neurotransmitters, chemicals
that carry nerve impulses from one neuron to the next.
(10) Like many other agents that affect neuron firing,
adenosine must first bind to specific receptors on
neuronal membranes. There are at least two classes
of these receptors, which have been designated A1 and
A2. Snyder et al propose that caffeine, which is struc-
(15) turally similar to adenosine, is able to bind to both types
of receptors, which prevents adenosine from attaching
there and allows the neurons to fire more readily than
they otherwise would.
For many years, caffeine's effects have been attri-
(20) buted to its inhibition of the production of phosphodi-
esterase, an enzyme that breaks down the chemical
called cyclic AMP.A number of neurotransmitters exert
their effects by first increasing cyclic AMP concentra-
tions in target neurons. Therefore, prolonged periods at
(25) the elevated concentrations, as might be brought about
by a phosphodiesterase inhibitor, could lead to a greater
amount of neuron firing and, consequently, to behav-
ioral stimulation. But Snyder et al point out that the
caffeine concentrations needed to inhibit the production
(30) of phosphodiesterase in the brain are much higher than
those that produce stimulation. Moreover, other com-
pounds that block phosphodiesterase's activity are not
stimulants.
To buttress their case that caffeine acts instead by pre-
(35) venting adenosine binding, Snyder et al compared the
stimulatory effects of a series of caffeine derivatives with
their ability to dislodge adenosine from its receptors in
the brains of mice. "In general," they reported, "the ability
of the compounds to compete at the receptors
(40) correlates with their ability to stimulate locomotion in
the mouse; i.e., the higher their capacity to bind at the
receptors, the higher their ability to stimulate locomo-
tion." Theophylline, a close structural relative of caffeine
and the major stimulant in tea, was one of the most
(45) effective compounds in both regards.
There were some apparent exceptions to the general
correlation observed between adenosine-receptor binding
and stimulation. One of these was a compound called
3-isobuty1-1-methylxanthine(IBMX), which bound very
(50) well but actually depressed mouse locomotion. Snyder
et al suggest that this is not a major stumbling block to
their hypothesis. The problem is that the compound has
mixed effects in the brain, a not unusual occurrence with
psychoactive drugs. Even caffeine, which is generally
(55) known only for its stimulatory effects, displays this
property, depressing mouse locomotion at very low
concentrations and stimulating it at higher ones.
1. The primary purpose of the passage is to
(A) discuss a plan for investigation of a phenomenon that is not yet fully understood
(B) present two explanations of a phenomenon and reconcile the differences between them
(C) summarize two theories and suggest a third theory that overcomes the problems encountered in the first two
(D) describe an alternative hypothesis and provide evidence and arguments that support it
(E) challenge the validity of a theory by exposing the inconsistencies and contradictions in it
2. According so Snyder et al, caffeine differs from adenosine in that caffeine
(A) stimulates behavior in the mouse and in humans, whereas adenosine stimulates behavior in humans only
(B) has mixed effects in the brain, whereas adenosine has only a stimulatory effect
(C) increases cyclic AMP concentrations in target neurons, whereas adenosine decreases such concentrations
(D) permits release of neurotransmitters when it is bound to adenosine receptors, whereas adenosine inhibits suchrelease
(E) inhibits both neuron firing and the production of phosphodiesterase when there is a sufficient concentration inthe brain, whereas adenosine inhibits only neuron firing
3. In response to experimental results concerning IBMX, Snyder et al contended that it is not uncommon for
psychoactive drugs to have
(A) mixed effects in the brain
(B) inhibitory effects on enzymes in the brain
(C) close structural relationships with caffeine
(D) depressive effects on mouse locomotion
(E) the ability to dislodge caffeine from receptors in the brain
4. According to Snyder et al, all of the following compounds can bind to specific receptors in the brain EXCEPT
(A) IBMX
(B) caffeine
(C) adenosine
(D) theophylline
(E) phosphodiesterase
5. Snyder et al suggest that caffeine’s ability to bind to A1 and A2 receptors can be at least partially attributed towhich of the following?
(A) The chemical relationship between caffeine and phosphodiesterase
(B) The structural relationship between caffeine and adenosine
(C) The structural similarity between caffeine and neurotransmitters
(D) The ability of caffeine to stimulate behavior
(E) The natural occurrence of caffeine and adenosine in the brain
6. The author quotes Snyder et al in lines 38-43 most probably in order to
(A) reveal some of the assumptions underlying their theory
(B) summarize a major finding of their experiments
(C) point out that their experiments were limited to the mouse
(D) indicate that their experiments resulted only in general correlations
(E) refute the objections made by supporters of the older theory
-5-
A compound-complex sentence consists of two sentences, and one or more adjective or adverb clauses.
EXAMPLE: John climbed to the top of the tree, but Sue, who was a bit clumsy, fell off half way up.
EXAMPLE: Since he was five, Frank has broken three fingers, two toes, and a knee cap
-6-
The whole point of this discussion is sentence variety. Don't be satisfied with writing only simple sentences--or only simple and compound sentences, for that matter. Varying your types of sentences will add versatility and rhythm to your writing style. Your reader will escape the monotony of simple sentence after simple sentence.
Besides lending variety to your writing, complex sentences can help you rank your ideas. You can show the reader that one idea is more important than another by putting the important idea in a sentence core and the unimportant idea in an adjective or adverb clause.
EXAMPLE: Main Idea: Larry attracts much attention.
Minor Idea: Larry wears elephant ears and duck feet rented from a costume shop.
THUS: Larry, who wears elephant ears and duck feet rented from a costume shop, attracts much attention.
OR: When he wears elephant ears and duck feet rented from a costume shop, Larry attracts much attention.
OR: Larry attracts much attention because he wears elephant ears and duck feet rented from a costume shop. ; however, he still walks across ice-covered telephone lines in the winter time. Caffeine, the stimulant in coffee, has been called"the most widely used psychoactive substance on Earth ."
Synder, Daly and Bruns have recently proposed that
caffeine affects behavior by countering the activity in
(5) the human brain of a naturally occurring chemical called
adenosine. Adenosine normally depresses neuron firing
in many areas of the brain. It apparently does this by
inhibiting the release of neurotransmitters, chemicals
that carry nerve impulses from one neuron to the next.
(10) Like many other agents that affect neuron firing,
adenosine must first bind to specific receptors on
neuronal membranes. There are at least two classes
of these receptors, which have been designated A1 and
A2. Snyder et al propose that caffeine, which is struc-
(15) turally similar to adenosine, is able to bind to both types
of receptors, which prevents adenosine from attaching
there and allows the neurons to fire more readily than
they otherwise would.
For many years, caffeine's effects have been attri-
(20) buted to its inhibition of the production of phosphodi-
esterase, an enzyme that breaks down the chemical
called cyclic AMP.A number of neurotransmitters exert
their effects by first increasing cyclic AMP concentra-
tions in target neurons. Therefore, prolonged periods at
(25) the elevated concentrations, as might be brought about
by a phosphodiesterase inhibitor, could lead to a greater
amount of neuron firing and, consequently, to behav-
ioral stimulation. But Snyder et al point out that the
caffeine concentrations needed to inhibit the production
(30) of phosphodiesterase in the brain are much higher than
those that produce stimulation. Moreover, other com-
pounds that block phosphodiesterase's activity are not
stimulants.
To buttress their case that caffeine acts instead by pre-
(35) venting adenosine binding, Snyder et al compared the
stimulatory effects of a series of caffeine derivatives with
their ability to dislodge adenosine from its receptors in
the brains of mice. "In general," they reported, "the ability
of the compounds to compete at the receptors
(40) correlates with their ability to stimulate locomotion in
the mouse; i.e., the higher their capacity to bind at the
receptors, the higher their ability to stimulate locomo-
tion." Theophylline, a close structural relative of caffeine
and the major stimulant in tea, was one of the most
(45) effective compounds in both regards.
There were some apparent exceptions to the general
correlation observed between adenosine-receptor binding
and stimulation. One of these was a compound called
3-isobuty1-1-methylxanthine(IBMX), which bound very
(50) well but actually depressed mouse locomotion. Snyder
et al suggest that this is not a major stumbling block to
their hypothesis. The problem is that the compound has
mixed effects in the brain, a not unusual occurrence with
psychoactive drugs. Even caffeine, which is generally
(55) known only for its stimulatory effects, displays this
property, depressing mouse locomotion at very low
concentrations and stimulating it at higher ones.
1. The primary purpose of the passage is to
(A) discuss a plan for investigation of a phenomenon that is not yet fully understood
(B) present two explanations of a phenomenon and reconcile the differences between them
(C) summarize two theories and suggest a third theory that overcomes the problems encountered in the first two
(D) describe an alternative hypothesis and provide evidence and arguments that support it
(E) challenge the validity of a theory by exposing the inconsistencies and contradictions in it
2. According so Snyder et al, caffeine differs from adenosine in that caffeine
(A) stimulates behavior in the mouse and in humans, whereas adenosine stimulates behavior in humans only
(B) has mixed effects in the brain, whereas adenosine has only a stimulatory effect
(C) increases cyclic AMP concentrations in target neurons, whereas adenosine decreases such concentrations
(D) permits release of neurotransmitters when it is bound to adenosine receptors, whereas adenosine inhibits suchrelease
(E) inhibits both neuron firing and the production of phosphodiesterase when there is a sufficient concentration inthe brain, whereas adenosine inhibits only neuron firing
3. In response to experimental results concerning IBMX, Snyder et al contended that it is not uncommon for
psychoactive drugs to have
(A) mixed effects in the brain
(B) inhibitory effects on enzymes in the brain
(C) close structural relationships with caffeine
(D) depressive effects on mouse locomotion
(E) the ability to dislodge caffeine from receptors in the brain
4. According to Snyder et al, all of the following compounds can bind to specific receptors in the brain EXCEPT
(A) IBMX
(B) caffeine
(C) adenosine
(D) theophylline
(E) phosphodiesterase
5. Snyder et al suggest that caffeine’s ability to bind to A1 and A2 receptors can be at least partially attributed towhich of the following?
(A) The chemical relationship between caffeine and phosphodiesterase
(B) The structural relationship between caffeine and adenosine
(C) The structural similarity between caffeine and neurotransmitters
(D) The ability of caffeine to stimulate behavior
(E) The natural occurrence of caffeine and adenosine in the brain
6. The author quotes Snyder et al in lines 38-43 most probably in order to
(A) reveal some of the assumptions underlying their theory
(B) summarize a major finding of their experiments
(C) point out that their experiments were limited to the mouse
(D) indicate that their experiments resulted only in general correlations
(E) refute the objections made by supporters of the older theory
INFINITIVE PHRASE
An infinitive phrase consists of an infinitive — the root of the verb preceded by to — and any modifiers or complements associated with it. Infinitive phrases can act as adjectives, adverbs, and nouns.
- Her plan to subsidize child care won wide acceptance among urban politicians. [modifies plan, functions as an adjective]
- She wanted to raise taxes. [noun-object of the sentence]
- To watch Uncle Billy tell this story is an eye-opening experience. [noun-subject of the sentence]
- To know her is to love her. [noun, predicate nominative]
- Juan went to college to study veterinary medicine. [tells us why he went, so it's an adverb]
GERUND PHRASE
Gerunds, verbals that end in -ing and that act as nouns, frequently are associated with modifiers and complements in a gerund phrase. These phrases function as units and can do anything that a noun can do. Notice that other phrases, especially prepositional phrases, are frequently part of the gerund phrase.
- Cramming for tests is not a good study strategy. [gerund phrase as subject]
- John enjoyed swimming in the lake after dark. [gerund phrase as object]
- I'm really not interested in studying biochemistry for the rest of my life. [gerund phrase as object of the preposition in ]
PARTICIPIAL PHRASE
Present participles, verbals ending in -ing, and past participles, verbals that end in -ed (for regular verbs) or other forms (for irregular verbs), are combined with complements and modifiers and become part of important phrasal structures. Participial phrases always act as adjectives. When they begin a sentence, they are often set off by a comma (as an introductory modifier); otherwise, participial phrases will be set off by commas if they are parenthetical elements.
- The stone steps, having been worn down by generations of students, needed to be replaced. [modifies "steps"]
- Working around the clock, the firefighters finally put out the last of the California brush fires. [modifies "firefighters"]
- The pond, frozen over since early December, is now safe for ice-skating. [modifies "pond"]
There are four basic types of sentences: 1) simple
4) compound-complex
-1-
A simple sentence consists of a core--subject, verb, object (sometimes) or complement (sometimes)--and modifying phrases (for example, prepositional phrases used as adjectives or adverbs
EXAMPLES: At noon on Tuesday during the summer Joe shoots at kittens and puppies with his bow and arrow.
NOTE: Phrases can often be placed either at the beginning or the end of a sentence, depending on how direct the writer wants to be.
EXAMPLE: With or without make-up, jewelry, or expensive clothes, Joan always looks like a zombie.
OR: Joan always looks like a zombie with or without make-up, jewelry, or expensive clothes.
(The second example is more direct
-2-
A compound sentence consists of two or more simple sentences.
These sentences are often combined with conjunctions, such as and, or, nor, but, yet, so, for, however, therefore, nevertheless, otherwise, consequently, etc.
EXAMPLE: Joe works in a manure factory downtown, and his wife Joan works in a perfume factory nearby.
EXAMPLE: Sarah saves five dollars out of each paycheck she receives
NOTE: In formal writing, compound sentences require either a comma before and, or, nor, but, yet, so, for, or a semi-colon before however, therefore, nevertheless, otherwise, consequently, etc
If there is no conjunction used between two simple sentences, a semi-colon or a period should be used instead.
EXAMPLE: Joe works downtown in a manure factory
-3-
A complex sentence can be one of two kinds: 1) one including an adjective clause
2) one including an adverb clause.
A complex sentence with an adjective clause consists of a simple sentence and an adjective clause.
Adjective clauses usually begin with: that, who, whose, whom, where, when, which. (These are adjective signal words.)
These clauses usually follow the word they modify, or at least appear very close to it
EXAMPLE: Mary is the person who dozes off continuously during church.
Susie is the girl whose brother takes his pet boa constrictor with him everywhere.
NOTE: Sometimes "that", "who", "whom", or "which", etc. is omitted from the adjective clause in a sentence--it is only implied. (This type of sentence is still complex.)
EXAMPLE: Jack is the guy Mary hit on the head with a bedpan. [Jack is the guy (who, that) Mary hit on the head with a bedpan.]
-4-
A complex sentence with an adverb clause consists of a simple sentence and an adverb clause.
Adverb clauses usually begin with such words as although, while, whereas, since, if, because as, as soon as, after, when. (These are adverb signal words.)
These clauses are often moveable
EXAMPLE: Although she gets sick from them, little Julie eats every mud pie she makes.
OR: Little Julie eats every mud pie she makes although she gets sick from them.
EXAMPLE: Jeff can pull the wings cleanly off ten flies in only thirty seconds when he concentrates on what he is doing.
OR: When he concentrates on what he is doing, Jeff can pull the wings cleanly off ten flies in only thirty seconds.
NOTE: Adverb and adjective clauses cannot stand alone
If a period is used after an adverb clause, this clause becomes a fragment.
