CH 21 HW (The Diversity of Protists)

You are a biologist who has just discovered that termites cannot digest wood, yet you have seen the damage termites can do to wood in homes. It has been suggested to you that this may be an example of mutualism. What does this mean to you?

A symbiotic relationship occurs where two individuals benefit from the relationship. The termite is providing food in the form of wood for something in the termite's gut, which is digesting the wood that can be absorbed by the termite.

_______ are phytoplankton with glassy shells. These shells consist of identical top and bottom halves that fit together.

Diatoms

_______ are alveolates with a round shape and two whip-like flagella that propel them through the water.

Dinoflagellates

_______ are excavates with double nuclei and multiple flagella.

Diplomonads

Species of red algae are useful for a variety of reasons, such as forming reefs and producing gelatinous substances with commercial uses. What is their most important contribution?

During photosynthesis they capture solar energy to help support nonphotosynthetic organisms in marine ecosystems.

Most scientists describe biodiversity in terms of the number of species that have been discovered and described in scientific journals. Roughly 1.8 million species have been described, although most scientists think there could be as many as 50 million species or more currently living on Earth. However, in the video, Craig Venter seems more interested in the total number of discovered genes (he gives a total number of 20 million genes in the video) than the total number of discovered species. Why is that?

For recombinant DNA technology or for the creation of synthetic life, only the gene that produces a particular desired product is needed, and not the entire organism that carried the gene.

_______ are euglenozoans with distinctly structured mitochondria.

Kinetoplastids

Many single-celled protists are considered predators because they ingest their food. How could this make them predators?

One major group uses their flexible membrane to engulf living organisms and consequently, harm their prey.

________ are excavates that live inside animals in a mutualistic relationship with their host.

Parabasalids

_______ are single-celled photosynthetic protists that live in the upper layers of Earth's lakes and oceans.

Phytoplankton

Which of the following statements best describes the DNA "watermarks" that Venter suggests adding to all lab-created organisms?

The watermarks can be used for tracing any descendants of the lab-created organisms.

Trichomoniasis is a sexually transmitted disease that causes unpleasant symptoms in females, including vaginal itching and discharge. What symptoms are displayed in males?

There are no symptoms in males.

Scientists like Craig Venter could choose to try to make any type of synthetic organism, from a bacterium to a mammal, but there are many things to consider when choosing a type of organism for research. Which of the following is a potential reason for choosing to create a type of organism other than a synthetic bacterium?

There is always a chance that a microscopic bacterium could escape undetected from the lab, and end up in the environment.

What is an important distinguishing characteristic of a group of protists sometimes called sporozoans?

They are not motile.

In traditional recombinant DNA technology, a desirable gene from one organism is inserted into the DNA of a host organism. However, to create a synthetic life form, Craig Venter's team actually builds the entire DNA molecule from individual DNA nucleotides. Why would it be harder to create a synthetic life form than to use recombinant DNA technology?

To create a synthetic life form, you would need to understand the role of every gene, and make sure all of the genes were included that are necessary for the organism to survive.

The chloroplast found within a photosynthetic protist is surrounded by four membranes. How can we account for this?

Two are from the originally engulfed photosynthetic bacterium; one is a protist membrane; the other is from the food vacuole produced by the protist originally containing the bacterium.

What would be an advantage to creating a synthetic organism, as compared to creating a genetically modified organism through recombinant DNA technology?

When creating a synthetic organism, you can more easily control the genes present in that organism, and make sure the organism cannot survive out in the environment.

Photosynthetic protists are collectively known as _______. Nonphotosynthetic protists are collectively known as _______.

algae; protozoa

What two characteristics are useful for supporting the photosynthetic mode of energy generation found in euglenids?

an eyespot (or photoreceptor) and a flagellum

Foraminiferans are marine protists that produce beautiful shells composed mostly of __________.

calcium carbonate

Which of the following have NOT already been done by scientists? -genetic engineering to create sheep that produce pharmaceuticals in their milk -fertilization of a human egg in a petri dish, called in vitro fertilization -cloning of a dinosaur from genes found in the blood of a fossil mosquito -gene therapy that uses a virus to deliver healthy genes into the cells of sick patients -cloning of mammals, such as sheep, cows, horses, and dogs

cloning of a dinosaur from genes found in the blood of a fossil mosquito

Which of the following are photosynthetic stramenopiles that encase themselves in protective shells of silica?

diatoms

Suppose you are walking along a Caribbean beach at night and as you watch the water gently lapping upon the shore, you notice small brilliant blue-green flashes of light. What do you suppose is causing them?

dinoflagellates

What subgroup of protists swims with one flagellum, are photosynthetic, and are common pond dwellers.

euglenids

Which of the following is a group lacking mitochondria?

excavates

Which of the following groups does not form a clade because its members are not all the decedents of a common ancestor?

protist

A major difference in early development found in plants and animals but not found in protists is that __________.

protist reproduction never includes the formation and development of an embryo

The flexible cell membranes of some single-celled protists can form extensions called _______ that reach out and engulf prey.

pseudopods

In the video, Craig Venter says, "We are trying to understand basic life, by learning how to now write the genetic code. So we start with the digital code in the computer, and four bottles of chemicals, and we actually build the DNA molecule from scratch." What chemicals are in those four bottles?

the four types of nucleotides (A, T, C, and G) that are the building blocks of DNA

What protist was responsible for the "late blight" that destroyed nearly the entire potato crop in Ireland about 1845?

water mold