Unit 7 Test SG Answers
Examples of plant responses to herbivory: thorns
defense against disease: cells near the pathogen area die to keep the pathogen from spreading
What is needed to increase the rate of movement of nutrients/gasses into organisms? Increased surface
area
Why can ectotherms survive food deprivation better than endotherms? Because they don’t expend
energy to regulate temperature
Characteristics of endotherms—regulate their body temperature vs ectotherms—their body
temperature changes with environmental temperature
Advantages of a complete digestive system over a gastrovascular cavity: complete allows for
specialization of functions
What is needed to break down macromolecules for absorption? Digestive enzymes
What type of reaction is this? Hydrolysis reactions (add water to break the molecules apart)
What is the function of the following organs:
Stomach—protein digestion, churning
Mouth—chewing, lubrication, starch digestion
large intestine—absorption of water
small intestine—digestion of all food types, absorption of all food types into the blood
stream
pancreas—secretes digestive enzymes into the small intestine
Pathway of oxygen from the atmosphere into the blood stream: alveoli->in and out of the cell lining the
lungs->in and out of the cell lining the capillary-> into the red blood cell
Why don’t sponges, cnidarians and flatworms need gas exchange systems? Because each cell is in direct
contact with the environment so each cell exchanges gasses through diffusion
Blood levels of what molecule control respiration rate? Levels of carbon dioxide in the blood
Pathway of carbon dioxide from a cell to the atmosphere: capillary small vein vena cava right
atrium  right ventricle  pulmonary artery  alveoli  bronchioles  bronchi  trachea 
larynxpharynx  nasal cavity  atmosphere
How is most carbon dioxide carried in the blood? As a bicarbonate ion
Describe the humoral immune response: uses antibodies made in plasma cells to defend against
pathogens
What do receptors on B cells and T cells bind to? Bind to antigens
What is the relationship between the MHC cells and T cells? T cells bind to antigens presented on MHC
by host cells
What does clonal selection in B cells result in? it produces plasma cells that make antibodies against the
pathogen
Why can we make so many different antibodies? Because of rearrangement of segments of DNA
molecules
What is the sequence of events in the primary immune response?
1. Antigens from pathogens bind to receptors on lymphocytes
2. Lymphocytes for the antigen multiply
3. Lymphocytes release antibodies
4. Pathogen dies
5. Memory cells give immunity
How do insects protect themselves from pathogens? They produce microbe killing chemicals and
proteins, their cells engulf pathogens through endocytosis
Why would a fresh water fish die if placed in sea water? Because it loses water from all its organs
Which organisms use these structures to remove nitrogen wastes:
Metanephridium—annelids (segmented worms)
Malpighian tubules—insects
Kidneys—mammals
flame bulbs (cells) –platyhelminthes (flatworms)
direct cellular exchange—marine invertebrates
Roles of ADH and RAAS in osmoregulation: ADH alters the amount of water the kidneys reabsorb; RAAS
stimulate sodium ion reabsorption
What is a presynaptic cell? Before the synapse A post synaptic cell? After the synapse. Note: a synapse
is a gap between the neurons.
How do impulses move across synapses? Using neurotransmitters that diffuse between the neurons.
Which ions move in what directions with the sodium/potassium pump? Sodium is pumped out,
potassium moves in.
Characteristics of ion channels in resting neurons: they open and close depending on stimuli and are
specific for different types of ions.
What is an action potential? What causes it? An action potential is the stimulation of a resting neuron.
They are caused by a neurotransmitter binding with a sodium ion channel which causes the channel to
open and sodium ions rush into the neuron. This is called depolarization because the inside of the
neuron becomes positively charged due to the change in relative ion concentration.
What is the difference in the speed of transmission of an impulse in a myelinated vs. non-myelinated
axon? They move more quickly in a myelnated neuron.
What is the sequence of events in transmission at a synapse?
1. The axon terminal of the presynaptic neuron depolarizes opening calcium ion channels
2. Calcium ions rush into the neuron causing release of the neurotransmitter
3. Neurotransmitters are released into the synapse which diffuse to the next neuron.
4. Neurotransmitters bind with receptors in the post-synaptic membrand.
5. Ion channels open, beginning depolarization of the next neuron.
What is depolarization ? What causes it? This is caused by a the opening of a sodium ion channel which
causes the sodium ions rush into the neuron. This is called depolarization because the inside of the
neuron becomes positively charged due to the change in relative ion concentration.
What is the function of acetylcholine? Causes contraction of skeletal muscles but relaxation of cardiac
muscle.
What are the functions of the different regions of the brain?
Occipital: vision
Temporal: smell and hearing
Frontal: speech
Parietal : taste, reading
Examples and function of 2 neurotransmitters
Motor neuron: takes impulses away from the spinal cord to the target organ
FRQ’s
Short:
Primary vs. secondary immune response
Study the graph on page 908 (7th edition textbook)
Primary response is the first exposure to the pathogen. It takes time to make antibodies against
it so you get sick.
Secondary response are subsequent exposures to the same pathogen. Your memory cells
remember the pathogen so you can make antibodies quickly which makes you immune.
Temperature regulation in mammals
Mammals are endotherms so they regulate their body temperature. If the temperature goes
down they shiver, they have vasoconstriction, they shift to producing heat instead of
ATP and they exhibit the pilomotor response. If the temperature goes up they sweat,
vasodialation occurs, and they produce ATP.
How a neuron transmits impulses
Within a resting neuron regions of the membrane depolarize in response to stimulus which
causes sodium ions to rush into the neuron. This causes depolarization in the region, which causes the
next segment to depolarize and this continues down the entire neuron. Between neurons, in the
synapse, neurotransmitters are released and diffuse across to the post synaptic cell which transmits the
impulse.
Long:
The relationship between the digestive, circulatory and respiratory systems.
Digestive and circulatory: all the digestive organs, what happens in each, which enzymes are
involved, where is each food type digested and absorbed, through what blood vessels and organs will
the absorbed molecules move to make it to cells
Mouth, esophagus, stomach, small intestine, large intestine
Villi of the small intestine , capillaries, vein, vena cava, right atrium, right ventricle, pulmonary artery,
capillaries in lungs, pulmonary vein, left atrium, left ventricle, aorta, artery, capillaries, cell
Between respiratory and circulatory: List all organs/structures in the circulatory and respiratory systems
that a molecule of oxygen would pass through to get to a body cell and that a carbon dioxide molecule
would have to pass through to get from the body cell to outside the body.
Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, capillaries, pulmonary vein, left
atrium, left ventricle, aorta, artery, capillaries, cell, oxygen in, carbon dioxide out, capillary, vein, vena
cava, right atrium, right ventricle, pulmonary artery, capillary, alveoli, bronchioles, bronchi, trachea,
larynx, pharynx, nasal cavity, atmosphere