UNIT II 1021

Most types of communication between cells utilize

the release of chemical signals by the cell sending the message

Coordinating body functions via chemical signals is accomplished by

the endocrine system

Tissues are composed of cells, and tissues functioning together make up

organs

Muscles are joined to bones by

tendons

The cells lining the air sacs in the lungs make up a

simple squamous epithelium

Salivary amylase digests

starches

A nutritional monomer that can be transported in the blood after a typical meal is

fatty acid

After ingestion by humans, the first category of macromolecules to be chemically digested by enzymes in the mouth is

carbohydrates

Pepsin is a digestive enzyme that

begins the hydrolysis of proteins in the stomach

Complex nutrients are digested and then absorbed into the lymph or bloodstream as

monomers

A skeletal muscle deprived of adequate ATP supplies will

enter a state where actin and myosin are unable to separate

The contraction of skeletal muscles is based on

myosin cross-bridges binding to actin and then flexing

Calcium ions initiate sliding of filaments in skeletal muscles by

binding to the troponin complex, which then relocates tropomyosin

An endoskeleton is the primary body support for the

cartilaginous fishes, including sharks

The absorptive epithelia in the gut are considered "polarized" because

the structures on the apical surface are different than those on the basal surface

In a survivably cold environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm

invests little energy in temperature regulation

Endothermy

is a characteristic of animals that have a fairly constant body temperature

Positive feedback differs from negative feedback in that

the positive feedback's effector responses are in the same direction as the initiating stimulus rather than opposite to it

The body's automatic tendency to maintain a constant and optimal internal environment is termed

homeostasis

Stomach cells are moderately well adapted to the acidity and protein-digesting activities in the stomach by having

a thick, mucous secretion and active mitosis of epithelial cells

In the digestive system, peristalsis is

smooth muscle contractions that move food along the esophagus

Ingested dietary substances must cross cell membranes to be used by the body, a process known as

absorption

The adaptations suited to a carnivorous diet include

bile salts

Cellulose-digesting symbiotic microbes exist in all of the following locations except

the stomach of a deep-sea giant tube worm

A skeletal muscle with abnormally low levels of calcium ions would be impaired in

initiating contraction

In a relaxed skeletal muscle, actin is not chemically bound to

myosin

The hydrostatic skeleton of the earthworm allows it to move around in its environment by

using peristaltic contractions of its circular and longitudinal muscles

Chitin is a major component of

the exoskeleton of insects

Positive feedback has occurred when

uterine contractions needed for the birthing process are expedited by the pressure of a moving baby in its mother's uterus

An example of an organism that has only behavioural controls over its body temperature is the

green frog

Stratified cuboidal epithelium is composed of

several layers of boxlike cells

An exchange surface in direct contact with the external environment is found in the

lungs

A matrix of connective tissue is apparent in

chondroitin sulphate of cartilage

Analysis of jawbones from the skeletal remains of a vertebrate animal reveal its dietary patterns owing to

the prevalence of specific kinds of teeth

A group of animals among which a relatively long cecum is likely to be found is the

herbivores

The cells that secrete acidic fluid in the stomach are

the parietal cells of the stomach

An enzyme with high activity in an acidic environment is

pepsin

All skeletal muscle fibres are both

striated and under voluntary control

Cardiac muscle cells are both

striated and interconnected by intercalated disks

All animals, whether large or small, have

each living cell in contact with an aqueous medium

With its abundance of collagenous fibres, cartilage is an example of

connective tissue

Use the following information to answer the next few questions.

It is wintertime and your pet lizard has somehow escaped into the backyard. After much searching, you find him basking on a rock in the sun trying to keep warm.

To conserve heat, it is likely that

blood vessels in the extremities are constricted

The bile salts

emulsify fats in the duodenum

Glandular secretions that are released initially as inactive precursors of digestive enzymes are the

protein-digesting enzymes

Because the foods eaten by animals are often composed largely of macromolecules, this requires the animals to have mechanisms for

enzymatic hydrolysis

The molar teeth of herbivorous mammals are especially effective at

grinding

Cattle are able to survive on a diet consisting almost entirely of plant material because

they have cellulose-digesting, symbiotic microorganisms in chambers of their stomachs

During muscle contraction,
I. actin filaments cross the M line.
II. the Z lines move closer together.
III. myosin forms cross bridges with actin.
IV. actin and myosin coil around each other.

I, II, & III

Skeletal, cardiac, and smooth muscle all have

thick and thin filaments

Most of the ATP supplies for a skeletal muscle undergoing one hour of sustained exercise come from

oxidative phosphorylation

All types of muscle tissue have

interactions between actin and myosin

An example of an ectothermic organism that has few or no behavioural options when it comes to its ability to adjust its body temperature is a

sea star, a marine invertebrate

Humans can lose, but cannot gain, heat through the process of

evaporation

In a multicellular animal, the circulatory system exchanges materials with the external environment using specialized exchange surfaces. Which of the following is not an example of such an exchange surface?

muscle

Connective tissues typically have

relatively few cells and a large amount of extracellular matrix

Which enzyme is involved in the breakdown of olive oil?

lipase

Digestive secretions with a pH of 2 are characteristic of the

stomach

The "motor unit" in vertebrate skeletal muscle refers to

one motor neuron and all of the muscle fibres on which it has synapses

The type of muscle tissue surrounding internal organs, other than the heart, is

smooth muscle

In a typical nerve cell, the nucleus is found in the

cell body

The panting responses that are observed in overheated birds and mammals dissipates excess heat by

evaporation

Breathing is accomplished via the rhythmic contraction and relaxation of

skeletal muscle

When the temperature of the outside air exceeds their internal body temperature, jackrabbits living in hot, arid lands will

constrict the blood vessels in their large ears to reduce transfer of external heat to the blood in their ears

An example of a connective tissue is the

blood

Most of the exchange surfaces of multicellular animals are lined with

epithelial tissue

Food moves along the digestive tract as the result of contractions by

smooth muscle

The nourishment, insulation, and support for neurons is the result of activity by the

glial cells

Muscle cells are stimulated by neurotransmitters released from the synaptic terminals of

motor neuron axons

Overlapping actin and myosin filaments are found in which section of the figure?

B

After breathing in an irritant, a normal response is to sneeze, loosening mucus along the respiratory tract. Which of the following types of epithelium form the mucous membrane?

pseudostratified columnar epithelium

An overheated and sick dog in a hot environment will have an impaired thermoregulatory response when its

body temperature increases to match the environmental temperature

Blood is best classified as connective tissue because

its cells are separated from each other by an extracellular matrix

The temperature-regulating centre of vertebrate animals is located in the

hypothalamus

The structure pictured in the figure is found in

cardiac & skeletal muscles

Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have

a closed circulatory system

Which of the following mechanisms are used to regulate blood pressure in the closed circulatory system of vertebrates?
I) changing the force of heart contraction
II) constricting and relaxing sphincters in the walls of arterioles
III) adjusting the volume of blood contained in the veins
IV) synthesizing new capillaries

I, II, and III

The semilunar valves of the mammalian heart

prevent backflow of blood in the aorta and pulmonary arteries

If a molecule of CO₂ released into the blood in your left toe is exhaled from your nose, it must pass through all of the following except

the pulmonary vein

Which of the following pairs of mammalian blood vessels has blood that is the least similar in its gas content?

the pulmonary vein and the jugular vein

If the delay in impulse from the atrioventricular node to the ventricles is reduced, this would result in

the incomplete emptying of atrial blood into the ventricles

When do atria contract?

during systole

Which of the following is the correct sequence of blood flow in reptiles and mammals?

vena cava → right atrium → right ventricle → pulmonary circuit

Circulatory systems have the primary benefit of overcoming the shortcomings of

the slow rate at which diffusion occurs across cells

Among the following choices, which organism likely has the highest systolic pressure?

giraffe

Fluid is filtered out of the bloodstream into the surrounding interstitial fluid at the arteriole end of systemic capillaries because

the hydrostatic pressure of the blood is greater than the osmotic pressure of the blood

If, during protein starvation, the osmotic pressure on the venous side of capillary beds drops below the hydrostatic pressure, then

fluids will tend to accumulate in tissues

The blood pressure is lowest in the

venae cavae

To become bound to hemoglobin for transport in a mammal, atmospheric molecules of oxygen must cross

fives membranes in and out of the cell lining the lung, in and out of the endothelial cell lining the pulmonary capillary, and into the red blood cell to bind with hemoglobin

The plasma proteins in humans

maintain the blood's osmotic pressure

Most of the carbon dioxide produced by humans is

converted to bicarbonate ions by an enzyme in red blood cells

The meshwork that forms the fabric of a blood clot is

fibrin

During a prolonged dive, mammals such as the Weddell seal do all of the following except

increase blood supply to muscles

An elderly patient has reduced mobility in his lower extremities. It has been observed that there are dark areas under the skin where blood has pooled. This pooling is most likely caused by

a reduction in blood flow through the veins

The material present in arterioles that is not present in capillaries is

circular smooth muscle cells that can alter the size of the arterioles

The velocity of blood flow is the lowest in capillaries because

the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system

The set of blood vessels with the lowest blood pressure driving flow is

the veins

How does the design of the circulatory network contribute to reducing blood pressure in the capillary beds avoid hemorrhage?

The total cross-sectional diameter of the arterial circulation increases with progression from artery to arteriole to capillary, leading to a reduced blood pressure

The set of blood vessels with the slowest velocity of blood flow is

the capillaries

In mammals, most gas exchange between the atmosphere and the pulmonary blood occurs in the

the alveoli

To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n)

four-chambered heart