Complex Life Cycles (Test Two)

Question 1

What makes complex life cycles different from normal life cycles?

Answer 1

They involve an abrupt developmental change in an organisms morphology, physiology, and behavior.

Question 2

Describe the mosquito life cycle.

Answer 2

1. Egg
2. Larva
3. Pupa
4. Adult (imago)

The change in form is associated with change in habitat

Question 3

What is the evolutionary advantage for mosquito life cycles and other like it?

Answer 3

It reduces competition between larva and adults for food and space

Question 4

Describe parasite’s life cycle.

Answer 4

1. Highly complex life cycles, involving more than one transformation
2. A change in habitat is a change in host or location within host

Example is “Toxoplasma gondii”

Question 5

What type of organism is and which Phylum are “Toxoplasma gondii” in?

Answer 5

1. Single celled Eukaryote
2. Phylum Apicomplexa

Question 6

Describe the type of parasite “Toxoplasma gondii” is, and what type of animals it can infect.

Answer 6

1. Intracellular parasite (invades inside cells)
2. Can infect virtually all warm-blooded animals

Question 7

What percent of the human population in the world is infected?

Answer 7

Between 30 and 50 percent

Question 8

Describe how “Toxoplasma gondii” reproduce.

Answer 8

They can reproduce both asexually and sexually

1. Sexual reproduction only occurs in cats (family Felidae)
2. Asexual reproduction occurs in virtually all warm-blooded animals

Question 9

Describe the life cycle of “Toxoplasma gondii”.

Answer 9

1. First Oocysts are produced in cats by sexual reproduction, and are passed in feces, which can infect hosts when ingested.
2. Oocysts then develop into tachyzoites, which are the rapidly multiplying version.
3. Once the tachyzoites localize in muscle tissue and the CNS, they convert to bradyzoites, which are tissue cysts.
4. Ingestion of meat that is contaminated by bradyzoites can result in infection as bradyzoites transform back into tachyzoites.

Question 10

What are the consequences of the disease toxoplasmosis?

Answer 10

1. Following exposure, mild flu symptoms.
2. In healthy adults no symptoms after (latent)
3. Can cause serious birth defects in infected during childbirth (blindness, organ failure, intellectual disabilities)
4. Infants, HIV/AIDS patients, or any immunocompromised patients can experience serious illness

Question 11

How does “Toxoplasma gondii” change the behavior of it’s infected hosts?

Answer 11

1. Reduces a rodent’s avoidance of cat odor, sometimes making it attractive.
2. Reduces motor performance

Question 12

How does “Toxoplasma gondii” benefit from a rodent’s change in behavior?

Answer 12

Because it make it more likely to end up in its sexually reproducing host, the cat.

Question 13

What is the parasite manipulation hypothesis?

Answer 13

The hypothesis that proposes some parasites have evolved mechanisms to influence their hosts to promote the parasites transmission.

Question 14

What Phylum are Dictyostelid in?

Answer 14

Phylum Amoebozoa

Question 15

Are Dictyostelid parasites?
Where do they live? What do they eat?

Answer 15

They are not parasites and they live in the upper layers of soil and leaf litter, eating bacteria.

Question 16

What determines the Dictyostelid life cycle?

Answer 16

Food abundance.

Question 17

Describe the Dictyostelid life cycle in more detail.

Answer 17

1. When food is abundant, they behave as individuals, which feed and divide normally, called the vegetative cycle.
2. When food is gone, they aggregate to form a slug-like (pseudoplasmodium)

Question 18

What are the general characteristics of a pseudoplasmodium?

Answer 18

1. Has an anterior and posterior
2. responds to the environment (migration)
3. Some cells have specialized functions

Question 19

What happens during the fruiting body stage of becoming a pseudoplasmodium?

Answer 19

1. Some cells sacrifice themselves, and die to become a stalk the others can climb
2. Those at the top form spores which are then carried away

Question 20

What is altruistic behavior?

Answer 20

Any behavior that reduces an individual’s relative fitness, but increases the fitness of others in the population.

Examples: meerkat sentry behavior, bee sting

Question 21

How to Dictyostelids display altruism?

Answer 21

The cells that form the stalk sacrifice themselves for the betterment of the group

Question 22

What is direct fitness?

Answer 22

Fitness through producing offspring.

Question 23

What is inclusive fitness?

Answer 23

Fitness through producing offspring, and providing aid that allows relatives to spread shared genes.

Question 24

How closely related are groups of individuals who display altruistic behavior?

Answer 24

They are highly related (90%)

Non-kin are excluded

Question 25

Describe the inclusive fitness theory.

Answer 25

The average fitness of an allele includes both its affect on the fitness of an individual, and its contribution o fitness of close relatives

Because related individuals share very similar alleles, by supporting the direct fitness of relatives, individuals can pass on their genes indirectly.