From Water to Land: 10 Amazing Types Of Amphibians

There are nearly 8,000 types of amphibians, including some of the most unusual and exciting creatures found on land and water.

About two million species of animals inhabit Planet Earth. More than that, scientists discover and categorize about 10,000 other new species every year. Animals are broken down into classes which include vertebrates and invertebrates, or animals with or without spines.

Amphibians belong to the vertebrate class along with birds, fish, mammals, and reptiles. All amphibians are cold-blooded, meaning they cannot generate body heat on their own. For that reason, they must rely on their environment to keep them cold or warm enough for survival.

Going further, most amphibians undergo a metamorphosis from a juvenile to an adult form. For example, frogs begin as tadpoles with gills and a tail. As they mature, they develop lungs. Over time, four legs replace most types of amphibians tails.

The Types of Amphibians

Amphibian species include three subgroups or orders. Firstly, there is the Order Anura which includes about 6,500 species of frogs and toads.

Secondly, the Order Caudata or Urodela includes about 680 species of newts and salamanders. Thirdly, Order Apoda or Gymnophiona, includes about 200 species of caecilians.

Frogs and Toads

Types of amphibians: European Common Frog (Rana temporaria) & European Toad (Bufo bufo) on a grassy patch of soil
European Common Frog (Rana temporaria) & European Toad (Bufo bufo): Image CC by 2.0 Generic, by Thomas Brown, via Wikipedia Commons

Frogs and toads typically have short bodies, webbed fingers and toes, and no tails. And, they usually have bulging eyes.

Newts and salamanders

yellow-spotted salamander, an amphibian, on a white background
Spotted salamander (Ambystoma maculatum): Image CC by 2.0, by Brian Gratwicke, via Wikipedia Commons

Newts and salamanders look similar to lizards and have short legs, skinny bodies, and long tails. Surprisingly, salamanders and newts have the remarkable ability to re-grow lost limbs and tails.

Caecilians

Caecilian: one of the types of amphibian with eggs in wet soil
Presumed Microcaecilia dermatophaga mother with eggs: Image CC by A 2.5 Generic, by Wilkinson M, Sherratt E, Starace F, Gower DJ (2013), via Wikipedia Commons

Caecilians don’t have any legs and resemble worms or snakes. That is because they mostly live underground, or in the substrate under streams. As a result, they have strong skulls and pointed noses to help them burrow through mud and dirt.

Fun Facts About Types of Amphibians

Amphibians are an evolutionary link between water-dwelling animals such as fish and land-dwelling animals such as mammals. Let’s be honest, they are some of the most fascinating animals on Planet Earth.

For example, amphibians have extremely primitive lungs. However, they have thin, moist skin that absorbs limited amounts of oxygen. So, you could say some types of amphibians breathe through their skin.

Another exciting fact about them, amphibians are carnivores and predators. But, they cannot chew their food. So, they swallow their prey whole.

Amphibians are also one of the planet’s most endangered animal species. It is believed that nearly half of the world’s amphibians are threatened species. That’s due to a combination of factors, including habitat loss, pollution, and climate change.

10 Amazing Types of Amphibians

Amphibians include some of the most amazing and unusual vertebrates found on earth. Much like their ancestors, most of them stick close to water.

We gathered a collection of photos of 10 of the most exciting types of amphibians currently roaming the earth, below. Then, we included a brief introduction to each one.

1. Axolotl

The axolotl is a type of salamander that is native to central Mexico. Unlike many other types of amphibians, axolotl larvae do not undergo metamorphosis when they reach maturity. As a result, they retain their gills, and tails, and are entirely aquatic throughout their life cycle.

photograph of an axolotl under wooden structure in a tank - one of the types of amphibian
Types of amphibians: Axolotl. Image via Instagram.

2. Fire Salamander

Fire salamanders are native to the forests of central and southern Europe. These types of amphibians stay near to ponds and streams, which they rely on for breeding. Another cool fact, they are active both night and day.

photograph of a fire salamander - a type of amphibian
Fire Salamander. Image via Instagram.

3. Golden Toad

The golden toad was native to the tropical mountain regions of Costa Rica, known as montane cloud forests. Sadly, golden toads are one of many types of amphibians thought to be extinct since they have not been seen since 1989.

photograph of a golden toad - a type of amphibian
Golden Toad. Image via Instagram.

4. Green Tree Frog

Green tree frogs are native to New Guinea and Australia. Their colors range from brown to green, depending on the surrounding air temperature. These are one of the most abundant types of amphibians dwelling in trees.

photograph of a green tree frog - a type of amphibian
Green Tree Frog. Image via Instagram.

5. Hellbender

Hellbenders are native to wetlands of Kentucky, Pennsylvania, and Tennessee. However, they are sometimes located in smaller numbers in the surrounding states. Sadly, hellbenders join other types of amphibians on the IUCN Red List of Threatened Species.

photograph of a hellbender - a type of amphibian
Hellbender. Image via Instagram.

6. Luristan Newt

These black and white spotted newts are native to the Luristan Province of Iran. While they look like cows, they are clearly amphibians. The Luristan newt is listed as “critically endangered” on the IUCN Red List of Threatened Species. However, they are currently protected under Iranian law.

photograph of a black and white spotted luristan newt - a type of amphibian
Luristan Newt. Image via Instagram.

7. Poison Dart Frog

The poison dart frog is native to the subtropical and tropical regions of South America. They can also be found in Central America. Bright colored dart frogs are extremely poisonous. However, dart frogs with cryptic or dull coloring have nominal toxicity. In fact, some are not toxic at all.

photograph of a poison dart frog - a type of amphibian
Poison Dart Frog. Image via Instagram.

8. Red-Eyed Tree Frog

The red-eyed tree frog is native to the Neotropical rainforests of Mexico and Central America. In addition to their bulging red eyes, these tree frogs have webbed orange feet and blue and yellow flanks. Luckily, due to their large number, they are listed as “least concerned” by the IUCN Red List of Threatened Species.

photograph of a red-eyed tree frog - a type of amphibian
Red-Eyed Tree Frog. Image via Instagram.

9. Endemic Tailed Caecilian

The endemic tailed caecilian is native to the tropical regions of Sri Lanka. Resembling a giant earthworm, endemic tailed caecilians range in size from 9 inches to nearly 16 inches. Additionally, the endemic tailed caecilian is listed as vulnerable by the IUCN Red List of Threatened Species.

photograph of a sri lankan endemic tailed caecilian - a type of amphibian
Sri Lankan Endemic Tailed Caecilian. Image via Instagram.

10. Tiger Salamander

The tiger salamander is native to the mountainous and lowland regions of the United States and Mexico. Unlike other types of amphibians, they tend to avoid water. Additionally, they can grow to lengths of 12 inches and larger.

photograph of a tiger salamander - a type of amphibian
Tiger Salamander. Image via Instagram.

What We Learned About the Types of Amphibians

We hope you enjoyed our article and accompanying photos of amazing and unique types of amphibians.

You have seen our favorite types of amphibians. Now we want to know about your faves. Using the comments section, let us know any unusual types of amphibians you would like to see included in future articles.

Featured image: A collage of various amphibians CC by ASA 3.0 Unported, by Various Artists: File:Litoria phyllochroa.JPG, File:Seymouria1.jpg, File:Notophthalmus viridescensPCCA20040816-3983A.jpg, File:Dermophis mexicanus.jpg, via Wikimedia Commons

Everything You Need to Know About the Calvin Cycle

The Calvin Cycle occurs during photosynthesis and consists of light independent redox reactions that convert carbon dioxide into glucose. This conversion happens in the chloroplast, or more specifically the stroma of the chloroplast. The chloroplast region is an area between the thylakoid membrane and the inner membrane of the organelle which is typically located in the leaves of plants.

This cycle used to create carbon sugars, mostly, was discovered by Melvin Calvin, Andrew Benson, and James Bassham in 1950 at the University of California. The used radioactive material to trace the pathways carbon atoms took during the carbon fixation step in plant life.

You've probably heard the Calvin Cycle called a few other names including the CBB Cycle, C3 Cycle, and dark reactions to name a few.

This process of carbon fixing by plants is essential to all life on the planet. Most new organic growth stems from plants converting carbon to sugars either directly or indirectly. Other plants, or animals, can use these sugars to forms more complex sugars and amino acids when they consume them. It all stems from little plants working day and night to capture light and water.

A Technical Take on the Calvin Cycle

The Calvin Cycle

The Calvin Cycle occurs during photosynthesis and is repeated until it forms a glucose molecule. Photosynthesis goes through two stages to create food and building materials for plants to grow. During the first stage, chemical reactions from light produce ATP and NADPH. The second stage is when the Calvin Cycle takes place. In this stage, carbon dioxide and water get converted to organic materials like glucose. These reactions are called dark reactions which confuses people, but they do not take place at night.

The short explanation of the Calvin Cycle is that it begins with carbon fixation. Carbon dioxide molecules are plucked out of the air to produce glyceraldehyde 3-phosphate. RuBisCO, an enzyme found abundantly around the planet, brings on the carboxylation of a 5-carbon compound and provides a 6-carbon compound that halves itself form two 3-phosphoglycerate. The enzyme phosphoglycerate kinase uses the phosphorylation to create biphosphoglycerate.

Next, the enzyme glyceraldehyde 3-phosphate dehydrogenase uses the reduction of biphosphoglycerate by NADPH. This is called the reduction reactions. Eventually, when the cycle ends, the reactions and reductions produce one glyceraldehyde 3-phosphate molecule per every three carbon dioxide molecules.

That’s a lot of massive words. What that means is the plant uses light and water to convert carbon dioxide into nutrients and oxygen. It takes six turns on the Calvin Cycle for the plant to produce a single glucose molecule. Now that we simplified the process, let's look at the chemical equation for the Calvin Cycle:

3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi (Pi = inorganic phosphate)

The Simplified Function of the Calvin Cycle

Simplified-Calvin-Cycle-diagram

How plants create sugar from sunlight, water, and carbon dioxide is complicated as you probably noted from the previous section. However, plants toil away day and night creating glucose, starch, and cellulose so they can grow. The Calvin Cycle plucks carbon molecules right out of the air and creates new plant growth.

The Calvin Cycle is vital to every ecosystem, and it reaches far beyond the plants using it. Plants are the building blocks of all the food in any ecosystem. Herbivores eat plants for energy and growth while carnivores eat herbivores for the same reasons. In the end, everything goes back into the ground and plants start the process all over again.

If plants stopped all their hard work tomorrow, it would only take a few days for animals to start feeling the effects and starving. Herbivores lose their food right away. Carnivores would follow behind the herbivores. Plants make most of the basic building blocks we all need to continue life as we know it. Without their hard work, we’d all be doomed.

While plants are supplying us with the building blocks, we need to continue living, and they help out the environment in other ways. Because the Calvin Cycle depends on carbon dioxide, plants indirectly play a role in regulating carbon dioxide and other gases proven to be harmful to the atmosphere. Plants perform an essential role in helping us clean the air we breathe.

The Calvin Cycle Step by Step

Calvin Cycle step by step

Carbon fixation is the first step. We explained it in brutal technical detail above, but let’s look at it in simpler terms in this section. A carbon dioxide molecule is plucked from the air and combined with a five-carbon acceptor molecule called ribulose-1,5-bisphosphate, or RuBP for short. The result is a six-carbon molecule.

The six-carbon molecule is split in half to form a set of new carbon molecules called 3-phosphoglyceric acid, or 3-PGA for short. The new three-carbon molecules are catalyzed by an enzyme called RuBisCo. This creates the simple sugar molecules the Calvin Cycle needs for stage two. On a side note, because it is used by every plant during photosynthesis, the RuBisCo enzyme if the most common catalyst on Earth. The result of this step is passed on to the next phase.

Step two of the Calvin Cycle is called the reduction step. The 3-PGA molecules created in the carbon fixation step are used in phase two to develop glyceraldehyde-3 phosphate or G3P for short. G3P is a simple sugar. This process uses energy and reactions captured during light-dependent stages of photosynthesis.

This step is called the reduction step because electrons are stolen from molecules created during photosynthesis and given to our new sugars. In chemistry, when you take electrons from a molecule, it's called a reduction hence the name of this stage. Technically, the electrons are donated and not taken. Taking electrons by force is called oxidation, and that's not what happens in this stage.

At this point, our plant has created sugar it can store for a long time and use for energy. Anything that eats this plant gets to take advantage of these sugars as well including humans. The plant may choose to use these stored molecules to form new plant materials or repair itself, but that’s not part of the Calvin Cycle so we won’t get into it. This is the end of the sugar-producing phase of the Calvin Cycle.

The final stage of the Calvin Cycle is called the regeneration step. Some of the G3P are held back and not used to make sugars. Instead, they are used to revitalize the five - carbon compound the Calvin Cycle needs to start the process over again. It takes six carbon molecules to make glucose, so plants have to go through the Calvin Cycle six times to make one glucose molecule.

Once the plant has completed this cycle six times, the Calvin Cycle ends and begins again. So, technically, the Calvin Cycle is all three steps done six times each. Plants repeat this process over and over during daylight hours. At night they continue to work making various compounds that don’t require light. This makes plants the most efficient lifeforms on the planet.

Bonus Information About Plants and Their Internal Food Factories

plants

We usually consider waste products bad or at least not edible. However, we need the waste materials plants to produce to survive. An essential waste, or by-product, plants produce is oxygen. While plants are using water and carbon dioxide to make sugars, they release oxygen into the air around them as a waste product.

The delicious fruits and vegetables we all enjoy get most of their flavor from the carbon sugars plants store for energy. From the crunchy stalk of the celery plant to the succulent meat of the peach, plants developed all using just carbon dioxide, water, sunlight, and a few minerals leeched from the soil. I think we can assume these tasty treats are little gifts from the plant kingdom.

The tiny organelles called chloroplasts on the surface of a plant’s leaves can move. Ok, they can’t move individually, but in many plants, they can turn the leaf, so it gets better exposure to sunlight. These plant-based solar cells help capture sunlight so being able to point yourself in the sun makes sense. Some plants take it to another level and bend their stalk or branches to help reach the sunlight.

Some Final Notes

photosynthesis diagram

The fantastic plants we ignore all around us are vital to our survival. They use energy from the Sun in little energy reactors called chloroplasts to do all sorts of cool things. If you glance at the bigger picture and oversimplify it, plants take light from the Sun and turn it into carbon sugars they can store for long periods of time. We could call them solar powered batteries if we want to be humorous about the process.

Plants pitch in and help everywhere they can from cleaning the air to enriching the soil they grow in for the next plants. Plants give us so many things from apples to steak. Without plants toiling away at the bottom of the food chain, nothing in the top of the food chain could survive. Every food we consume comes from plants either directly or indirectly.

Your Guide To Your First Earthworm Dissection

Earthworms play essential roles in many ecosystems. They help introduce oxygen to the soil and mix it up. As they tunnel through the ground, they enrich the soil and push it toward the surface where it's easier for plants to get to the nutrients. You can see the organs that help these worms do their jobs by dissecting an earthworm.

Safety First

woman showing earthworms

Safety is critical in all aspects of our lives. It may seem trivial in a controlled environment like a school biology lab, but it's not, and all safety rules should be followed. They are in place to protect you and your classmates, so don't skip any regulations just because you think it will be ok or those rules don't seem to apply to your circumstances. The basic common-sense rules are:

  • Wear safety gear when necessary like goggles, gloves, and aprons.
  • Most preserved specimens contain formaldehyde, so wash them first.
  • Do not play with lab equipment or instruments such as scalpels and scissors.
  • Do not eat any parts of your specimen. Yes, there is an apparent reason for this rule.

Your lab should have the rules and safety measures available plus your instructor will go over them with you. Don’t assume the only rules are the ones we list here. The type of lab and type of specimen determine the rules. Ask for a copy of the rules if you don’t see one posted in the lab. Your teacher should be close by most of the time to help you guide you as well.

Always wear safety goggles and gloves. If you have to carry a sharp instrument, hold it with the pointed end pointing down and away from your body. Don't rush or run while holding a scalpel or scissors. Never carry a knife or scissors by any part other than the handle. Scalpels are razor sharp, and it only takes a split second for them to cut you open.

Keep your station clean and tend to any spills immediately unless they pose a breathing hazard. Dispose of any blades, gloves, aprons, and specimens according to the established rules in your lab. Your teacher will probably explain all the rules to you, but don’t wait to ask if you aren’t sure what to do. Teachers are there to help educate you and keep you safe.

Earthworm Dissection Guide

earthworm dissection

Earthworms are great for helping you understand simple organisms and basic anatomy. They'll help you get a grasp on lab safety before you progress to larger specimens like pigs or frogs. As a bonus, they're small and soft, so handling them is much more comfortable as well.

The first step is to examine the exterior of the earthworm. Earthworms are segmented works, so they look like a long stack of small rings. They don't have a head or any limbs, but they do have a fascinating exterior anatomy to study. The anterior end of the earthworm is a little fatter than the posterior. When you locate the anterior end of the work, pin it to the dissecting pan or tray.

Earthworms are annelids which means their bodies are composed of multiple ring-like sections or segments. This part may not be on your teacher's list, but it's always interesting to count the segments while you study the exterior anatomy of the earthworm. While you count, notice the small setae on the ventral surface. These little bristles help the worms move through the dirt with ease.

Each segment along the worm's exterior has small pores. These pores excrete the sticky film you find when you run your finger along a live worm. You may need a magnifying glass or small microscope to see them. It depends on the size of your earthworm specimen and your eyesight as well.

From the anterior end of the worm, count your way down to segment fourteen. Typically, this is where the oviducts are located. The oviducts release the eggs when the worm reproduces. The exciting part is the next segment after the oviducts; it contains the sperm ducts. Earthworms have both male and female reproductive organs.

Further down the worm at segment 31 is the clitellum. It secretes a sticky mucus that binds two earthworms together while the mate. It develops a cocoon to hold the eggs and sperm after mating is finished. Earthworms are simple worms, but fantastic at the same time. Their exterior anatomy is fascinating to study.

Earthworms are hermaphroditic which means they have both female and male reproductive organs. Eggs come from the ovaries inside segment fourteen, sometimes thirteen. It can be hard to count the segments on small worms. Worms have testes which can form in segments near the oviducts. Study these segments and see if you can find the reproductive organs on your specimen.

When worms mate, they get stuck together briefly to help keep the reproductive organs aligned. Sperm from both worms travels into the other worms seminal receptacle. The clitellum creates the cocoon which moves along the outside of the worm to collect the semen and the eggs. The eggs are fertilized outside the worm in the cocoon.

By now, you should have a good understanding of the exterior anatomy of your earthworm specimen. Remove the pin from the anterior end of the earthworm and place it on its ventral side, then put the pin back in the anterior end of the worm. The ventral side of the worm is a little flatter than the dorsal side, and it may be a lighter color.

Carefully and slowly make a shallow incision using your scalpel from the anterior end of the work to the clitellum. Never cut toward your body or fingers. Be extra careful and keep the incision shallow, so you don't cut into the worm's digestive system and internal organs. Use your forceps to spread the worm open and pin the sides of its body to your dissection pan or tray.

The inside of the worm should be exposed now. You may want to lightly sprinkle water over the worm to keep it from drying out while you study the inside of it. The interior part of the walls is called the septa. See if you can tell the difference. If possible, ask your teacher to point them out and help you see the different layers.

Now, the internal digestive organs should be exposed and available for study. Starting with the mount on the anterior end of the worm, locate the organs. The first organ you see is the pharynx. The worm's esophagus protrudes from the pharynx. About halfway down your incision are the crop and gizzard. Skip the other organs for now and find those two.

The crop is essentially a stomach. It stores food until the food is moved to the gizzard which grinds it up. The food leaves the gizzard and goes into the intestine, much like it does in humans, and travels to the anus. Along the way, the worm's intestines absorb nutrients from the food the gizzard crushed and ground up. Earthworms don't eat dirt. The consume organic materials found in the soil.

Make your way back up to the crop. If you look above the crop on the anterior side, you’ll find five pairs of aortic arches. This is the worm’s version of a heart. The hearts are located around the esophagus, and they connect to the dorsal blood vessel. That's the worm's version of an artery. Most earthworms can take direct damage to half their aortic arches and live.

Move your attention back to the pharynx at the anterior end of the worm. Locate the cerebral ganglia beneath the pharynx on the dorsal side. You may need to use your forceps to move some organs around to get a good look at it. The ventral nerve starts at the cerebral ganglia and runs the length of the worm. It may be hard to see if it is too small.

They are simple creatures speaking purely on their anatomy, but how their bodies and mating works are truly amazing. If you have time, go back over this tutorial again and study the worm longer. When you finish exploring, make sure you clean your workstation and dispose of your specimen correctly. Dispose of your lab gear according to the lab rules. Wash your hand thoroughly with soap and water.

Some Final Notes

earthworm

Earthworms are vital to the health of our soil. The improve drainage, help stabilize the land, and add nutrients to the ground. Worms feed on organic materials they find in the dirt. Their bodies use the nutrients they need and deposit what's left back into the soil as waste. Fortunately for plants, that waste is usually nitrogen-rich along with other nutrients plants need to grow.

Their worm tunnels help loosen the soil which aids plants in root development. We could go on and on about the benefits of earthworms. If you follow our guide to dissecting earthworms and read our interesting facts along the way, we’re sure you’ll be able to dissect an earthworm specimen safely. You may even appreciate these simple creatures a little more when you are done.

Taxonomy Quiz

Taxonomy
  1.  Which of the following pairs is MOST closely related?
    dog & tapeworm
    tapeworm & bacteria
    mushroom & tree
    ameba & bacteria
  2. Organisms in the Kingdom Animalia are:
    multicellular & heterotrophic
    multicellular & autotrophic
    unicellular & autotrophic
    unicellular & autotrophic
  3. Which of the following groups would contain the largest number of organisms?
    class
    order
    phylum
    family
  4. A scientific name contains information about its:
    family & species
    genus & species
    phylum & order
    class & family
  5. What do plants and animals have in common?
    both are heterotrophic
    both are autotrophic
    both are prokaryotic
    both are eukaryotic
  6. The current classification system was devised by:
    Aristotle
    Plato
    Linnaeus
    Darwin
  7. Instead of phylum, plants use which category?
    division
    subspecies
    class
    subkingdom
  8. If two organisms are in the same phylum, they must also be in the same:
    class
    species
    family
    kingdom
  9. Which kingdom contains “extreme halophiles”?
    eubacteria
    archaebacteria
    fungi
    protista
  10. A dichotomous key is used to:
    locate an organism
    identify an organism
    divide a kingdom
    interbreed species

Score =
Correct answers:

Virus Study Guide

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Name: 

Virus Quiz

 

 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
Viruses are considered nonliving because
a.
they cannot reproduce by themselves.
b.
they are not made up of cells.
c.
they cannot carry out metabolism by themselves.
d.
All of the above
 2.
The study of viruses is a part of biology because
a.
they belong to the kingdom Eubacteria.
b.
they are about to become extinct.
c.
they are living organisms.
d.
they are active inside living cells.
 3.
Biologists now know that viruses
a.
are the smallest organisms.
b.
consist of a protein surrounded by a nucleic acid coat.
c.
contain RNA or DNA in a protein or lipid-protein coat.
d.
all form the same crystalline shape.
 4.
The capsid of a virus is the
a.
protective outer coat.
b.
cell membrane.
c.
nucleus.
d.
cell wall and membrane complex.
 5.
Viruses are classified according to
a.
whether they contain RNA or DNA.
b.
the shape of their genome.
c.
whether they have a membrane envelope.
d.
All of the above
 6.
All viruses have
a.
cytoplasm.
c.
mitochondria.
b.
ribosomes.
d.
None of the above
 7.
Tobacco mosaic virus
a.
is able to be crystallized.
b.
causes disease in tobacco plants.
c.
is smaller than a bacterium.
d.
All of the above
 8.
Scientists first began to study viruses because they
a.
were seen through a microscope.
b.
could not be seen but caused disease.
c.
formed crystals.
d.
were made of cells.
 9.
Viruses that use reverse transcriptase to cause their host cells to transcribe DNA from an RNA template are called
a.
bacteriophages.
c.
retroviruses.
b.
antibodies.
d.
capsoviruses.
 10.
Which of the following contains only RNA?
a.
a prion
c.
a viroid
b.
a virus
d.
All of the above
 11.
Unlike viruses, prions
a.
are capable of reproducing outside of a host cell.
b.
are composed only of protein.
c.
can cause brain infections.
d.
can be treated with antibiotics.
 12.
A typical virus consists of
a.
a protein coat and a cytoplasm core.
b.
a carbohydrate coat and a nucleic acid core.
c.
a protein coat and a nucleic acid core.
d.
a polysaccharide coat and a nucleic acid core.
nar001-1.jpg
 13.
Refer to the illustration above. Which structure could possibly be made of RNA?
a.
structure 2
c.
structure 4
b.
structure 3
d.
structure 5
 14.
Refer to the illustration above. Which structure is found outside the cell after the cell is infected?
a.
structure 1
c.
structure 3
b.
structure 2
d.
structure 4
 15.
Viruses
a.
are cellular organisms.
b.
reproduce only in living cells.
c.
have nuclei and organelles.
d.
are surrounded by a polysaccharide coat.
 16.
Animal viruses often infect only specific host cells because
a.
the virus must have the same DNA as the host cell.
b.
the host cell must have specific receptors for proteins on the virus surface.
c.
viruses have receptors for host cell glycoproteins.
d.
the enzymes of the virus can attach only to specific host cells.
 17.
In which cell cycle(s) does viral DNA become integrated into the host cell’s DNA?
a.
lytic
b.
lysogenic
c.
neither lytic nor lysogenic
d.
both lytic and lysogenic
 18.
Antibiotics are ineffective against viral infections because
a.
host cells protect the viruses.
b.
viruses have enzymes that inactivate the antibiotics.
c.
antibiotics interfere with cellular processes that viruses do not perform.
d.
viral protein coats block the antibiotics from entering the virus.
 19.
Which of the following is not a viral disease of humans?
a.
hepatitis
b.
SARS
c.
shingles
d.
All of the above are viral diseases of humans.
 20.
Which of the following is not linked to cancer?
a.
Ebola virus
c.
hepatitis B virus
b.
human papillomavirus
d.
Epstein-Barr virus
 21.
Which of the following human activities is most closely associated with the emergence of viruses not previously seen in humans?
a.
absence of a vaccination program
b.
crowded living conditions
c.
clearing of forests for housing
d.
eating uncooked meat
 22.
Most scientists think that early viruses originated from
a.
other viruses.
b.
existing cell parts.
c.
animals.
d.
spontaneous generation.
 23.
HIV causes AIDS by
a.
converting a proto-oncogene to an oncogene.
b.
damaging a person’s blood vessels.
c.
destroying the covering of a person’s nerves.
d.
gradually destroying a person’s immune system.
 24.
Which of the following is not a vector of viral diseases?
a.
mosquitoes
c.
prions
b.
ticks
d.
humans
 25.
Which of the following has been the most successful at fighting viral diseases?
a.
vaccination
c.
drug therapy
b.
vector control
d.
Both a and b
 26.
Most scientists believe that viruses first appeared on Earth ____ living cells appeared.
a.
after
b.
a very long time before
c.
at the exact time when
d.
immediately before
 

Completion
Complete each statement.
 27.
The protein coat of a virus is called a(n) ____________________.

 28.
Viruses can vary in size and ____________________.

 29.
A virus that transcribes DNA from an RNA template is called a(n) ____________________.

 30.
An enzyme called _________________________ manufactures DNA that is complementary to a virus’s RNA.

 31.
____________________ are viruses that infect bacteria and have a polyhedral head and a helical tail.

 32.
All viruses reproduce by taking over the reproductive machinery of a(n) ____________________.

 33.
Viruses that infect a host cell and have their nucleic acid replicated but do not harm the host cell are in a(n) ____________________ cycle.

 34.
The replication of a temperate virus includes the ____________________ cycle.

 35.
The virus that causes AIDS is called _________________________.

 36.
Some viruses are thought to induce ____________________, a disease characterized by uncontrolled cell division.

 37.
The Ebola virus, the SARS virus, and hantavirus are examples of ____________________ viruses.

 38.
In the ____________________ cycle, viruses destroy the host cell.

 39.
Chickenpox and ____________________ are caused by the same virus.

 

Problem
 40.

A new disease has suddenly appeared and scientists are trying to determine whether the disease agent is a virus or a bacterium. They collect the following information:

1.      The disease can be transmitted through the air.
2.      The disease agent is too small to be seen under a light microscope.
3.      There are no known antibiotics that are effective against the disease.
4.      The genetic material of the disease agent is DNA.
5.      The disease agent cannot be cultured using any known culture medium.

Is the disease agent most likely a bacterium or a virus? Explain your answer. Write your answer in the space below.

 

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Quiz Viruses

Name: 

Viruses

 

 

True/False
Indicate whether the sentence or statement is true or false.
1.
Although viruses do not consist of cells, biologists consider them to be living because they are capable of reproduction.
2.
Some viruses have a membranous envelope surrounding the protein coat that helps them gain entry into host cells.
3.
Viruses consist of RNA or DNA surrounded by a coat of protein.
4.
Prions are the smallest known particles that are able to replicate.
5.
A virus can only reproduce by controlling a cell.
6.
Once a virus enters either a lytic or a lysogenic cycle, it cannot change to the opposite type of cycle.
7.
Prophages and proviruses can both enter lytic cycles and destroy host cells.
8.
People can contract the influenza virus more than once because the virus tends to mutate rapidly, avoiding the actions of the immune system.
9.
Smallpox is caused by bacteria.
10.
Chickenpox and shingles are caused by the same virus.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
11.
The study of viruses is a part of biology because
a.
they belong to the kingdom Eubacteria.
b.
they are about to become extinct.
c.
they are living organisms.
d.
they are active inside living cells.
12.
The capsid of a virus is the
a.
protective outer coat.
c.
nucleus.
b.
cell membrane.
d.
cell wall and membrane complex.
13.
A membranous envelope surrounding some viruses may be composed of
a.
lipids.
c.
glycoproteins.
b.
proteins.
d.
All of the above
14.
viruses : nucleic acids::
a.
water : ice
c.
simplicity : complexity
b.
brick : wood
d.
a jigsaw puzzle : individual pieces
15.
A typical virus consists of
a.
a protein coat and a cytoplasm core.
b.
a carbohydrate coat and a nucleic acid core.
c.
a protein coat and a nucleic acid core.
d.
a polysaccharide coat and a nucleic acid core.
viruses_files/i0180000.jpg
16.
Refer to the illustration above. Which labeled structure could possibly be made of RNA?
a.
Structure “B”
c.
Structure “D”
b.
Structure “C”
d.
Structure “E”
17.
In which type of cell cycle(s) does viral DNA become integrated into the host cell’s DNA?
a.
lytic
c.
neither lytic nor lysogenic
b.
lysogenic
d.
lytic and lysogenic
18.
A prophage differs from a provirus in that
a.
a prophage contains DNA, while a provirus contains RNA.
b.
a prophage is formed during a lysogenic cycle, while a provirus is formed during a lytic cycle.
c.
a prophage contains DNA found in the infecting virus particle, while a provirus contains DNA produced from viral RNA.
d.
a prophage becomes integrated into a host cell’s DNA, while a provirus cannot become integrated into a host cell’s DNA.
19.
Which of the following is not a virus linked to cancer?
a.
Ebola
c.
hepatitis B
b.
human papillomavirus
d.
Epstein-Barr
20.
Which of the following human activities is most closely associated with emerging viruses?
a.
absence of a vaccination program
c.
clearcutting of forests
b.
crowded living conditions
d.
eating uncooked meat

 

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