Lab Test 1 Questions Flashcards
What are the adaptations seen in Euglena towards the autotrophic mode of nutrition?
- Euglena have a paraflagellar body (photoreceptor) at the base of its flagella which collects light.
- The red spot covers the paraflagellar body to protect it from intense sunlight/radiation.
- Euglena contains chloroplast which contains pigment that harvests light to photosynthesize.
- It has chlorophyll a.
Explain the body organization in colonial Volvox. Why are such colonial forms considered as precursors of multicellular organisms?
- Volvox are made of 500- 50,000 cells arranged along the periphery of a hollow mucillaginous sphere.
- It has germ cells and flagellated, somatic cells. Such colonies exhibit a division of labor and cell to cell communication.
- They are said to be precursors of mutlicellular organisms, because it helps to explain how cellular communication and division of labor evolved to make tissue system in multicellular organisms.
Explain the structure, mode of feeding and locomotion in amoeba.
- Amoeba is a unicellular protist with an** undefined shape. It has a true nucleus, cytoplasm, a plasma membrane **and other organelles such as mitochondria and vacuoles.
- Amoeba feed by phagocytosis and pinocytosis; it digests food in its food vacuole and releases waste through exocytosis.
- They move by extending their plasma membrane to create pseudopodia.
Explain the structure of radiolaria and foraminifera. Discuss their importance.
Radiolarians are siliceous single celled protozoans. They also have arm like extensions that look like spikes.
Foraminiferans are protists that build roundish shells made of calcium carbonate. They have reticulopodia networks.
Foraminiferans are important for assessing past climate changes.
Radiolarians are important
Explain the mechanism of asexual & and sexual reproduction in Paramecium. Discuss the significance of sexual reproduction
Asexual reproduction in Paramecium occurs by binary fission. When a paramecium matures, it mitotically divides transversely into two identical daughter cells.
They sexually reproduce by a process known as conjugation. This is where two mature paramecia line side by side and then fuse together.
Sexual Reproduction is significant because it ensures variation and survival among the organism. Overtime organisms evolve and develop methods of resistance towards environmental factors. When they cross reproduce, they pass on their resistant genes to other generations.
Discuss the significance of the association of Trychonympha & and termites.
Trychonympha are mutualistic protozoans found in the gut of termites and wood roaches. They break down cellulose in the wood and thus helps the termite in digestion of the wood. The Trichonympha also feeds on the fragments of wood.
Explain the structure of Vorticella.
Vorticella is a single-celled, bell-shaped ciliate that have stalks to attach itself to substrates.
What are spicules? Classify the spicules seen on the slide based on their shape. What are their functions?
describe structure and then function
Spicules are sharp, pointed or needle-like structures that are found in sponges. They can be various shapes and sizes and are unique to each specie. They are used for structural support as well as for protection against predators.
Monaxon and Triaxon
Identify the type of aquiferous system you observed in the l.s of Grantia. Describe the structure of the aquiferous system
Syconoid Aquiferous system
Water enters a Grantia sponge through several incurrent canals (ostia) and passes through internal pores or prosopyles that act like flood gates or valves. Water then enters the spongocoel and then exits through the osculum at the top.
What are Gemmules? What is its structure, how is its structure adapted to serve the function, and what is its importance to the sponge?
Gemmules are seed-like capsules formed by sponges to tide over unfavorable conditions.
Nutrient laden archaeocytes are enveloped in 3 layered spongin envelope with an opening at one pole called a micropyle.
Because of its nutrient rich center, it allows the spore to tide over unfavorable conditions and survive; thus allowing it to be germinated.
Explain the structure of Hydra, a typical polyp.
A Hydra is a cylindrical form of Cnidarian. It has an orient mouth upward and tentacles around its oral disc. It has a pedal disc at its aboral end which it uses to attach to substrates.
Explain the structure of the Obelia colony and explain the phenomenon of polymorphism with respect to Obelia.
Obelia is a stalk like Cnidarian form with a polymorphic body. It has two stages; a polyp stage and a medusa stage.
Each of its branches has
three types of zooids – the polyp, the medusae and the blastostyles.
The polyp has a vase like body, the medusae are saucer shapedand the blastocyles are club shaped and lack mouth and tentacles.
Explain the habitat, and habit of Cassiopeia and the significance of its association with zooxanthellae.
Cassiopeia jellyfishes live in warm, shallow waters such as shallow mangrove swamps, mudflats and canals.
They are mostly found upside down and close to the surface of water. This is because they use symbiotic algae found in their oral arms to photosynthesize.
The algae are provided with shelter and in return the zooxanthellae provide the jellyfish with its nutritional needs.
Explain the structure of Aurelia.
Aurelia is a medusa form of Cnidarian with an umbrella shaped body and is radially symmetrical. The margins of its umbrella bears tentacles and there is a central stalk called a manubrium which extends into the mouth.
Explain the different larval stages of Aurelia seen in the lab.
The first stage of its life cyce is the Planula; a ciliated larvae. The planula then settles down and attaches to a substrate. The larvae then looses its cilia and it then develops into a Schyphistoma. The scyphistoma then undergoes strobilation and a Strobila is then produced. From the Strobila arises many juvenile jellyfishes known as Ephyra.
