The growth and death of these colonial cyanobacteria formed stromatolites from accumulated layers of dead cells

Which of the following statements about the endosymbiont hypothesis explains the origin of eukaryotic cells?

Mitochondria and chloroplasts originated from symbiotic relationships between two prokaryotic cells.

Infolding of the plasma membrane, known as ________, is believed to be responsible for the evolution of membranous structures in the eukaryotic cell, such as the nucleus and endoplasmic reticulum.

endocytosis

What structure found in both chloroplasts and mitochondria links them to prokaryotes rather than to eukaryotes?

circular DNA molecules

Which of the following statements is not true?

Chloroplasts were originally large, free-living eukaryotic cells.

Which of the following is a characteristic of both Archaea and Eukarya?

introns

What evidence supports the hypothesis that Eukarya shared a common ancestor with Archaeans more recently than with Bacteria?

Introns are found in the genomes of the Archaeans and Eukarya but not in the Bacteria.

A probable intermediate step in the evolution of multicellularity from unicellular ancestors in the Eukarya was the formation of ________.

colonies

Colonies

Colonial aggregations would increase the capacity of members to withstand environmental fluctuations

Which of the following statements supports the hypothesis that life developed near hydrothermal vents in the sea floor?

Reducing conditions exist near hydrothermal vents, along with chemicals essential for life.

Reducing conditions

Reducing conditions are necessary for the spontaneious formation of some of the organic molecules necessary for living cells

Which of the following supports the controversial theory that life had an extraterrestrial origin?

is is possible that organic compounds arrived by meteor impact

Protocells:

might have been the precursors of early cells

The maintenance of the internal environment in a stable state is called ______

homeostasis

In most animals, specialized cells are organized into ________.

Tissues

Which of the following statements about tissues is correct?

All tissues can be classified into one of four basic tissue groups

Which of the following is not one of the four basic tissue groups found in animals?

adipose

Cilia are often found on the free surface of cells in which basic tissue group?

epithelial

What is the function of the layer of glycoproteins called the basal lamina?

It fixes epithelium to underlying tissues.

Glands with ducts are known as ________.

exocrine

Which of the following statements about connective tissues is true?

living cells in connective tissue are often outweighed by extracellular matrix (ECM) material

What kind of cell secretes most of the collagen and other proteins in loose connective tissue?

fibroblast

What is the function of ligaments

They connect bones to each other

Which of the following statements about cartilage is correct ?

1. Cartilage is resistant to compression 2. Cartilage supports the larynx and trachea in humans 3. Chondrocytes are living cells in cartilage 4. Cartilage is made up of a matrix of the glycoprotein chondroitin sulfate

What kind of cell is specialized for fat storage?

adipocyte

What is the primary characteristics of all muscle tissue?

the ability to contact

Which structure in nervous tissue functions in physical support and electrical insulation ?

glial cells

Components of blood?

1. platelets 2. plasma 3. leukocytes 4. erythrocytes

Organ systems are coordinated and integrated to accomplish which collective tasks ?

1. Sensing and responding to changes in the environment 2. Reproducing and nourishing offspring. 3. Protecting the body against injury and disease-causing agents. 4. Acquiring nutrients and distributing them throughout the body.

The primary purpose of all organ systems is to:

maintain homeostasis

Which factors of the internal environment are homeostatically regulated?

1. Volume and pressure of blood plasma

2. Water and NaCl balance

3. pH

4. O2 and CO2 concentrations

What is the primary mechanisms of homeostasis?

negative feedback

Which of the following statements about the internal environment is not correct ?

A single-celled organism exchanges nutrients and wastes through the internal environment

You would expect the bones of a growing child to have extremely active

osteoblasts

An examination of the arrangement of bones in the hand is an example of

an anatomical study.

Which of the following cell junctions are responsible for allowing the bladder lining to stretch, thus accommodating increasing volumes of urine?

anchoring junctions

You observe a tissue with one free surface with several layers of cells attached to a basal lamina. This is an example of

epithelial tissue.

The major disadvantage of using stem cells derived from human embryos was:

they were difficult to maintain in culture.

Which tissue is best described as a sparse distribution of cells surrounded by an open network of collagen and elastin fibers?

loose connective tissue

If you were presented with a tissue sample that contained long rows of cells surrounded by parallel bundles of collagen and elastin fibers, that tissue would most likely be

fibrous connective tissue

A person takes a medication that blocks their neurons' ability to be stimulated by a specific chemical signal. What part of the neuron is most likely being affected by the medication?

dendrites

Which major tissue category often has more extracellular matrix material than cellular material?

connective tissue

The evolution of multicellularity was important for organisms for all of the following reasons EXCEPT?

It allows for mutualisms with single cell organisms

The cells of which tissue are connected by gap junctions?

cardiac and smooth muscle

An examination of the processes of muscle contraction in fishes is an example of

a physiological study.

Which of the following organ systems are NOT involved in temperature regulation or secretions of hormones?

skeletal system

Which organ system is NOT required for the maintenance of homeostasis within an organism?

reproductive system

Which of the following organ systems is responsible for eliminating metabolic wastes from the body?

excretory, respiratory, and circulatory system

Which of the following human tissue cell types can be over a meter in length?

neurons

The structure of a tissue is determined by

the structure and organization of the cell cytoskeleton, the type and organization of the extracellular matrix and the junctions holding cells together.

Which of the following is a correct statement about the formation of sustainable human stem cell cultures?

In which of the following excretory tubule segments in mammals does about 65 percent of the water from the filtrate get reabsorbed?

proximal convoluted tubule

Which of the following excretory tubule segments in mammals consumes the most ATP?

ascending segment of the loop of Henle

Osmoreceptors help the body deal with dehydration in part by stimulating release of

`antidiuretic hormone.

Compared to uric acid, using urea as the main form of nitrogenous waste requires

less energy and more water.

Osmolarity is the outcome of the

total solute concentration in a solution.

As filtrate moves through the ____ in mammals it generally undergoes a dramatic decrease in osmolarity.

ascending segment of the loop of Henle

The filtration rate at the Bowman's capsule is kept constant in response to small variations in blood pressure by the actions of

the juxtaglomerular apparatus.

The urine of marine mammals is ____ when compared to ____.

hyperosmotic; seawater

Because it has no aquaporins, water is generally trapped in the ____ in mammals.

ascending segment of the loop of Henle

Suppose that you have a cell with a membrane that is permeable to water but not to Na+ or Cl− or any other solute. There is more NaCl outside the cell than inside the cell, and the osmolarity of the cell is higher than that of the solution surrounding the cell. Which of the following should occur?

Overall, the cell should take up water.

Which of the following is the main form of nitrogenous wastes released by aquatic invertebrates to their environment?

ammonia

The osmoreceptors that the body uses to detect and react to situations such as dehydration are located in the

hypothalamus

Which of the following are typically osmoconformers?

sharks

The movement of some molecules and ions out of excretory system tubules and back into body fluids is

reabsorption.

Which of the following is secreted by cells in the juxtaglomerular apparatus in response to a significant drop in blood pressure or blood volume?

renin

Which of the following excretory tubule segments in mammals allows water to exit but does not allow ions or urea to exit?

descending segment of the loop of Henle

Molecules and ions reabsorbed from the nephron reenter the blood at the

peritubular capillaries.

The selective movement of specific small molecules and ions into excretory system tubules is

secretion

In which of the following excretory tubule segments in mammals does essentially all of the glucose and amino acids from the filtrate get reabsorbed?

proximal convoluted tubule

In mammals, the glomerulus is located within the

Bowman's capsule

The nonselective movement of water and a number of solutes into excretory system tubules is

filtration

Which of the following, produced from a blood protein as part of the chain of events in response to a significant drop in blood pressure, quickly raises blood pressure by constricting many arterioles?

angiotensin

Which component of neural signaling determines the appropriate response to a perceived stimulus?

integration

The ________ of a neuron conduct(s) signals away from the cell body to another neuron or effector.

axon

The function of astrocytes in the vertebrate CNS is to ________.

maintain the concentration of ions in fluid surrounding neurons

Gaps in the myelin sheath that speed transmission of nerve impulses are called ________.

nodes of Ranvier

Electrical synapses are differentiated from chemical synapses by the fact that only electrical synapses ________.

allow ions to flow directly between presynaptic and postsynaptic neurons

Which statement about neurons is not correct?

A neuron has many axons.

Using microelectrodes inserted through the plasma membrane of isolated neurons, researchers have measured a resting potential of about ________.

-70mV

The Na+/K+ pump creates an imbalance of these ions inside and outside the cell by pumping ________.

three Na+ ions out of the cell for every two K+ ions in

Which of the following statements about action potentials is correct?

Following an action potential, the membrane potential is briefly hyperpolarized.

K+ channel activation gates open when:

The action potential reaches its peak

Which of the following describes propagation of an action potential along an unmyelinated axon?

Adjacent firing segments induce the next segment of the axon to fire

Which of the following choices best describes the manner in which action potentials are propagated via saltatory conduction?

Action potentials are propagated via diffusion of Na+ ions within the myelinated axon.

What happens when the myelin sheath is progressively lost from axons and replaced by hardened scar tissue?

Transmission of action potentials is blocked, causing paralysis

Equilibrium potentials are calculated in order to:

predict ion movement across the cell membrane

Which of the following does not occur when an action potential reaches the chemical synapse at a presynaptic neuron?

Ligand-gated ion channels open in the presynaptic membrane.

Metabotropic neurotransmitters are differentiated from ionotropic neurotransmitters by the fact that only indirect neurotransmitters can:

Bind to G-protein-coupled receptors in the postsynaptic membrane.

Which of the following would be expected to occur if a neurotransmitter opened a ligand-gated ion channel that allows Cl- to flow into a neuron and K+ to flow out?

The membrane becomes hyperpolarized.

Which of the following correctly differentiates IPSPs and EPSPs from action potentials?

IPSPs and EPSPs are graded potentials but action potentials are all-or-nothing events.

Summation of several EPSPs will not occur if:

Several different presynaptic neurons sequentially cause EPSPs that occur after the previous EPSP has died down.

One neuron may have as many as ________ connections to other neurons.

100,000

The binding of a neurotransmitter to ligand-gated Cl− channels will cause ____ in the postsynaptic membrane.

hyperpolarization

The minimum level of depolarization required to initiate an action potential in an excitable cell is called the

threshold potential.

Which of the following structures is NOT actively involved with saltatory conduction?

Na+/K+ pumps

Which of the following does NOT involve K+

depolarization

The refractory period of a neuron plasma membrane is important because

it ensures that an impulse will travel in a one-way direction.

Which of the following components of a neural signaling pathway are correctly arranged from beginning to end?

reception -->transmission-> integration --> transmission--> response

The transmission of information from one neuron to another has been found to occur by all of the following mechanisms EXCEPT

chemical signals transmitted through electrical connections.

If the K+ channels of an excitable plasma membrane were blocked by the action of a drug, which of the following would be disrupted?

repolarization and hyperpolarization

A graded, subthreshold change in the postsynaptic membrane potential that moves it toward threshold is called a(n)

EPSP

Assume a neuron receives EPSPs and IPSPs from several adjacent neurons. How might that neuron's threshold potential be reached, causing it to produce its own action potential?

temporal and spatial summation

Which cells are part of the vertebrate peripheral nervous system?

afferent, motor and efferent neurons

When threshold potential is reached, which of the following occurs?

The activation gates of Na+ channels open

In vertebrates, the neurotransmitter acetylcholine

1. can act as a direct neurotransmitter between neurons and muscle cells

2. can make it more difficult for some postsynaptic membranes to reach threshold.

Which glial cell(s) is/are only found in the peripheral nervous system?

Schwann cells

The binding of a neurotransmitter to ligand-gated K+ channels will cause ____ in the postsynaptic membrane.

hyperpolarization

For which axon might you expect action potential propagation to be the fastest?

a myelinated axon with a large diameter

The neuron resting membrane potential is established due to all of the following EXCEPT

the distribution of ions inside and outside an axon.

Action potentials are propagated in a one-way direction down a neuron plasma membrane because

the adjacent channels upstream from the action potential are in their refractory period

What neuron location has the greatest density of voltage-gated Na+ channels, resulting in the lowest threshold potential along a neuron?

axon hillock

During an action potential, the membrane potential can reach as high as

+30 mV

The disease multiple sclerosis causes myelin degeneration in vertebrate nervous systems. Knowing this, what symptoms/effects might you NOT expect in a person with multiple sclerosis?

memory loss

Symptoms/effects of patients with multiple sclerosis?

1. tissue numbness

2. muscular weakness

3. slowed action potential transmission

4. faulty coordination of movements

The binding of a neurotransmitter to ligand-gated Na+ channels will cause ____ in the postsynaptic membrane

depolarization

A nerve net is a feature of which of the following groups of organisms?

cnidarians

Vertebrate nervous systems are differentiated from those of invertebrates because only vertebrate nervous systems are:

are composed of a dorsal, hollow, fluid-filled brain and nerve cord

The peripheral nervous system of a planarian consists of ________.

longitudinal nerves connecting ganglia with the rest of the body

The structure of the human brain that integrates signals from the eyes, ears, and muscle spindles with motor signals is the ________.

cerebellum

Which of the following regions of the adult brain develops from the embryonic diencephalon?

thalamus and hypothalamus

In humans, higher functions such as thought, action, and communication take place in the ________.

cerebrum

Signals from the CNS travel via ________ neurons of the ________ nervous system to effectors that carry out responses.

efferent; peripheral

The somatic and autonomic systems are two divisions of the ________ nervous system.

efferent

Voluntary movement of skeletal muscles is controlled by the ________ nervous system.

somatic

When a person is frightened, the force and rate of the heartbeat is increased by ________ neurons.

sympathetic

Smooth muscle contractions that move materials through the small intestine are stimulated by ________ neurons.

autonomic, parasympathetic

Gray matter within the spinal cord consists of ________.

nerve cell bodies and dendrites only

Meninges are:

layers of connective tissues that protect the brain and spinal cord

The blood-brain barrier:

1. is made up of capillaries in the brain that are sealed together by tight junctions

2. does not block lipids soluble molecules such as steroids, alcohol, and anesthetics

3. protects the brain and spinal cord from viruses, bacteria, and toxic substances that may be circulating in the blood

4. prevents most small molecules and ions dissolved in the blood from entering the cerebrospinal fluid

PET scans record brain activity by ________.

measuring changes in blood flow or metabolic activity

The reticular formation in the brain stem functions primarily in ________.

integrating sensory input

Which of the following centers in the brain functions as a switchboard that routes information about emotional experiences through the limbic system?

amygdala

Brain damage to the temporal lobe is most likely to result in problems ________.

distinguishing one sound from another

Memory is ________.

storage and retrieval of a sensory or motor experience

Studies on people whose corpus callosum has been surgically severed have revealed that:

Information stored in memory on one cerebral hemisphere is not available to the other hemisphere.

The portion of the nervous system that is responsible for increasing heart rate, as well as increasing movement of the intestines, is the

autonomic nervous system.

Which of the following brain structure−function sets are incorrectly matched?

hypothalamus − controls voluntary movements

The blood-brain barrier does not

block glial cells from migrating to the spinal cord

Which of the following animals do NOT use echolocation?

moths

Animals that use echolocation

1. dolphins

2. bats

3. porpoises

4. whales

Many aquatic invertebrates use this structure to perceive changes in their body's position and orientation.

statocysts

Autonomic nervous system pathways have ____.

two neurons

Areas of the brain that are associated with higher functions, such as communication, forethought, and action, develop from the

forebrain &

telencephalon

Organisms can perceive different intensities of a stimulus by

an increase in the frequency of action potentials generated by an afferent neuron as well as an increase in the numbers of afferent neurons generating action potentials, but without any change in the intensity of individual action potentials generated by the neurons.

Of the following statements concerning the sympathetic and parasympathetic branches of the nervous system, which is true?

The sympathetic system generally produces an increased physical activity, while the parasympathetic system produces a decrease in physical activity.

An organism that ingests smaller organisms that it filters from the water is an example of a ________.

suspension feeder

Most animals digest their food through ________.

primarily extracellular digestion

In animals with a saclike digestive system, undigested food waste is expelled through the ________.

mouth

Which of the following structures found in birds does not have an analogous counterpart in both earthworms and grasshoppers?

pancreas

Which of the following lists the correct order in which food passes through humans?

stomach, small intestine, large intestine

Which of the following is not one of the four layers of the gut?

mesentery

Food is physically prevented from prematurely leaving the stomach by ________.

a sphincter

Which of the following structures prevents food from entering the nasal passages during swallowing?

soft palate

Which of the following cell types is not found in the stomach?

brush-border cells

Brush-border cells are found in the:

small intestines

The surface area of intestinal epithelial cells is greatly increased by ________.

microvilli

Which of the following organs does not release fluids into the duodenum to aid in digestion?

spleen

Which of the following molecules can enter intestinal mucosa cells?

monosaccharides

Which of the following substances produced by the liver is a waste product from old red blood cells?

bilirubin

The appendix is attached to the ________.

cecum

Which of the following hormones is not directly involved in controlling digestion in humans?

thyroxin

Overall control of digestion is exerted by the ________.

hypothalamus

Which of the following types of teeth are adapted for clipping off blades of grass?

incisors

A relatively long intestine is a characteristic of animals that eat ________.

plants

Layers of mammalian gut in order from outside inward, toward the lumen

1.serosa

2. muscularis

3. submucosa

4. mucosa

Chief cells produces _____.

pepsinogen

What is a lysosome's role in intracellular digestion?

Enyzmatic digestion

The digestion of lipids in humans begins in the

small intestines

Most peptic ulcers are caused by

bacteria

Digestion of starches begins in which structure of the digestive tract ?

mouth

Which of the following statements are correct regarding the human digestive tract ?

The large intestine does not contain villi and is larger in diameter and smaller in length than the small intestine.

What vitamin could be toxic in large amounts?

Vitamin A

A diet that does not contain any dark green vegetables, whole grains, yeast, or lean meats may result in a deficiency of which vitamin?

folic acid

Which of the following enzymes is NOT produced by the pancreas?

pepsin

Enzymes produced in the pancreas

1. carboxypeptidase

2. trypsin

3. amylase

4. lipase

Place the five steps of digestion in most animals with a digestive tube in the proper order.

1. mechanical processing

2. secretion of enzymes

3. enzymatic hydrolysis

4. absorption

5. elimination

Which vitamin is produced in humans when exposed to sunlight?

Vitamin D

When fat enters the duodenum, it stimulates release of which hormone?

Cholecytokinin (CCK)

In which organ do we classify food as chyme?

Stomach

What function does the presence of alkaline components in pancreatic juice serve?

Creates an optimum environment for digestion in the small intestines

Which of these structures produces a hormone that activates secretion of enzymes within it?

Stomach

Which part of a bird's digestive system contains sand and rocks to aid in mechanical digestion?

Gizzard

Which pairs of vitamins is produced within the human body ?

Vitamin D and K

Heartburn is caused by ____.

the gastroesophageal sphincter remaining a little open

Inhalation

Passage of air into the lungs to supply the body with oxygen

Exhalation

Passage of air out of the lungs to expel carbon dioxide

Erythropoietin is produced in the _____.

kidneys

Oprain-Haldane hypothesis on primordial earth

They proposed that, rather than being an oxygen-rich (oxidizing) atmosphere as it is now, the early atmosphere was a strongly reducing atmosphere, due to the concentration of substances such as hydrogen (H2), methane (CH4), ammonia (NH3), and water, which are fully reduced—they contain the maximum possible number of electrons and hydrogens

Primordial atmosphere would have an abundance of _______.

electrons and hydrogens for reduction reactions, which could create organic molecules from inorganic elements and compounds.

Absence of _______ in the primitive atmosphere is essential to the Oparin- Haldane hypothesis.

Oxygen

Experiment supported the Oparin-Haldane hypothesis

reducing atmosphere consisting of H2, CH4, and NH3, as well as H2O. After one week of running the apparatus, as much as 15% of the carbon was now in the form of organic compounds, including amino acids.

After running the apparatus for only a week, Miller found a large assortment of organic compounds in the water, including:

1. urea

2. amino acids

3. lactic acids

4. formic acids

5. acetic acids

What aspect of the Miller-Urey experimental design ruled out the possibility that amino acids were synthesized by living organisms such as bacteria?

The experiment used boiling water to create water vapor. bacteria would have been killed by the boiling water.

Did the Miller-Urey experiment support the Oparin-Haldane hypothesis?

Yes

Theory of origin of life (2):

1. Life might have originated near oceanic hydrothermal vents

2. Organic compounds arrived by meteor impact.

Why is the reducing nature of early Earths atmosphere key to the Oparin-Haldane theory of the origin of molecules necessary for life?

Only in a reducing atmosphere can amino acids be produced from simpler chemicals and energy.

Why are amino acids crucial for life?

Without amino acids there can be no life. Amino acids are the building blocks of life.

RNA world model

states that the first genes and enzymes were RNA molecules that are Ribozymes. (RNA molecules capable of catalyzing biochemical reactions--may have functioned both as informational molecules and as catalysts in protocells, without requiring protein enzymes for catalytic reactions).

Modern day viruses

carry out this RNA-to-DNA reaction using the enzyme reverse transcriptase

Basic steps of how life might have originated:

1. abiotic(nonliving) synthesis of organic molecules such as amino acids

2. assembly of complex organic molecules from simple molecules, including protein or RNA or both

3. aggregation of complex organic molecules inside membrane-bound protocells. Once the information system fully developed in protocells, and it could replicate, and the protocells could divide, they became true living cells.

Radiometric dating

technique used to date a rock and is based on the decay of isotopes in the rock.

Stromatolites

Fossil stromatolites are layers of carbonate or silicate rock that resemble present-day stromatolites

Biosignatures

particular organic molecules in sedimentary rocks that would have been formed by cellular activity.

Microfossils

A microfossil is the remains of a cell that is decayed and been filled in by calcium carbonate or silica.

The mitochondrion is thought to have originated from an aerobic prokaryote that lived as an endosymbiont within an anaerobic prokaryote.

Features of archeans that are typical pf bacteria

1. circular DNA genome in a nucleoid region without a surrounding nuclear envelope.

2. No membrane-bound organelles in the cytoplasm.

Features of archeans thats are typical of eukaryotes:

1. Presence of introns in some of their genes

Unique features of archeans:

1. features of gene and rRNA sequences

2. features of cell wall and plasma membrane structure that are found nowhere else among living organisms

Prevalent theory

multicellular eukaryotes arose by the aggregation of cells of the same species into a colony.

Endosymbiont origins for mitochondria

An anaerobic prokaryotic is proposed to have ingested an aerobic prokaryote, which persisted in the cytoplasm, continuing to respire aerobically. A gradual process of mutal adaptation transformed the cytoplasmic aerobes into mitochondria

All animals are heterotrophs

they eat other organisms to acquire energy and nutrients

All animals are motile

able to move from place to place

sessile

unable to move from place to place.

Example: mussels and barnacles (only motile in their larval stages and then eventually settles down)

All animals share similarities :

1. cell-to-cell junctions

2. molecules in their extracellular matrices

3. structure of their ribosomal RNA's

Animal orgins:

colonial, flagellated protists in which cells became specialized for specific functions and a developmental reorganization produced two cell layers.

Characteristics of plants:

1. autotrophic

2. usally sessile

3. cell walls

Characteristic of animals

1. heterotrophs

2. No cell wall

3. motile

Parazoa , or sponges

lacks tissues

Eumetazoa

Have tissues

Three concentric primary cell layers:

1. Endoderm (innermost layer)

2. Ectoderm (Outermost layer)

3. Mesoderm (Between the endo and ectoderm)

Diploblastic

includes only two layers, endoderm and ectoderm.

asymmetrical

irregular shape

Ex. Sponges

Eumetazoans exhibit two body symmetry patterns:

1. Radial symmetry

2. bilateral symmetry

Radial symmetric animals include:

1. Cnidaria (hydras, jellyfishes, and sea anemones)

2. Ctenophora (comb jellies)

Bilateral symmetric animals have:

anterior, posterior, dorsal, and ventral surfaces

Cephalization

development of an anterior head where sensory organs and nervous-system tissue are concentrated

Acoelomate

lack cavity

Ex. flatworms

Psuedocoelomate

have a fluid-or organfilled space between the gut and the muscles of the body wall, that is partially lined by tissues derived from mesoderm.

Ex. roundworms

Coelomate

has a fluidfilled body cavity that is completely lined by the peritoneum. Mesenteries surround the internal organs and suspend them within the coelom.

Hydrostatic skeleton

Structure consisting of muscles or fluid that, by themselves, provide support for the animal or part of the animal; no rigid support, such as bone, is involved.

Protostomes

blastopore develops into the mouth first

Deuterostomes

blastopore develops into the anus first

Cleavage

Mitotic cell divisions of the zygote that produce a blastula from a fertilized ovum.

Protosomes undergo

determinate cleavage: each cell's developmental path is determined as the cell is produced.

Deuterostomes undergo

indeterminate cleavage: developmental fates of cells are determined later

Origin of mesoderm and coelom in protosomes:

originates from a few specific cells near the blastopore. As the mesoderm grows and develops, it splits into inner and outer layers. The space between the layers is called schizocoelom

Orgin of mesoderm and coelom in deuterostomes

mesoderm forms from outpocketings of the archenteron. The space pinched off from the archenteron by the outpocketing mesoderm is called an enterocoelom.

Segmentation

segmented animals may survive damage to the organs in one segment, because those in other segments perform the same functions.

Tissue

a group of cells that share a common structure and function

functional significance of the coelom?

Space within internal organs can move independently of the body wall muscles. The fluid within it provides protection for internal organs. In some animals the coelom functions as a hydrostatic skeleton

kidneys release renin, which causes convertion of angiotension I (produced by liver) into angiotension II that in turn stimulates aldosterone release. This mechanism is used by the kidneys to control blood pressure and blood volume

Liver secretes

angiotension (a prohormone)

Kidneys secrete

1. erythropoietin which signals production of RBCS

2. renin that converts angiotensin to angiotension I

parietal cells of the stomach produce _____.

1. Hydrochloric acid (HCL)

2. Intrinsic factor

Accessory digestive organs

teeth, tongue, gallbladder, salivary glands, liver, and pancreas

Six essential activities:

1. Ingestion

2. Propulsion

3. mechanical digestion

4. Chemical digestion

5. absorption

6. defecation

Mucous neck cells

secretes acid mucus

Chief cells of the stomach produce pepsinogen and then ...

Pepsinogen is activated to pepsin by HCl in the stomach

Spontaneous reactions of hydrogen, nitrogen, and carbon would have produced:

1. ammonia (NH3)

2. Methand (CH4)

Why was it important for the atmosphere to be a reducing rather than oxidizing?

Because there was an abundance of electrons and hydrogens for reduction reactions, it would create organic molecules from inorganic elements and compounds using natural sources of energy

What if there was oxygen in the atmosphere during primordial earth?

If oxygen was present, newly formed molecules would have broken down by oxidation