Exam (elaborations)
ZOL1501 EXAM PACK 2023
- Institution
- University Of South Africa (Unisa)
QUESTIONS AND ANSWERS
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ZOL1501EXAM
PACK 2023
QUESTIONS AND
ANSWERS
, Prepare by Spirogyra
23 May 2019
Learning Unit 1
Architectural patterns of Animals
Five major grades of organization
1. Protoplasmic grade of organization .
‣ Protoplasmic grade characterizes unicellular organisms
‣ All life functions are confined within boundaries of a single cell, the fundamental unit of
life
‣ Within Cell, protoplasm is differentiated into organelles capable of performing
specialized functions
2. Cellular grade of organization
‣ Cellular grade of organization is an aggregation of cells that are functionally
differentiated
‣ A division of labor is evidence, so that some cells are concerned with, for example,
reproduction and other nutrition. Some flagellates, such as volvox, that have a distinctive
somatic and reproductive cells are placed at cellular level of organization. Many
authorities also place sponges at this level.
3. Cell-tissue grade of organization
‣ A step beyond the preceding in an aggregation of similar cells into patterns or layers
and organized to perform a common function, to form a tissue. Sponges are considered
by the authorities to belong to this grade, although jellyfish and their relatives(Cnidaria)
more clearly demonstrates the tissue plan. Both groups are still largely of cellular grade
of organization because most cells are scattered and not organized into tissues.
‣ An excellent example of a definite tissue in Cnidarians is nerve net, in which nerve cells
and their processes form a definite tissue structure with the function of coordination.
4. Tissue-organ grade of organization
‣ An aggregation of tissues into organs is a further stage in complexity.
‣ Organs are usually composed of more than one tissue and have a more specialized
function than tissues.
‣ This is the organization level of Platyhelminthes(flatworms), in which well defined organs
such as eyespots, proboscis, and reproductive organs occur.
ZOL1501 Exam Prep
1
, Prepare by Spirogyra
23 May 2019
‣ In Platyhelminthes, the reproductive organs transcend the tissue-organ grade are
specialized into a reproductive system.
5. Organ-system grade of organization
‣ When organs work together to perform some function, we have the highest level of
organization, an organ system.
‣ Systems are associated with the basic body functions such as circulation, respiration,
and digestion.
‣ The simplest animals having this type of organization are Nemertean worms, which have
a complete digestive system distinct from the circulatory system.
‣ Most animal phyla demonstrates this type of organization.
Distinguish amongst spherical, radial, bilateral and biradial symmetry and refer to one
representative example for each
1. Spherical symmetry means that any plane passing through the body into equivalent or
mirrored halved. E.g Volvox
2. Radial symmetry forms that can be divided into similar halves by more than two planes
passing through the longitudinal axis. E.g Hydra
3. Biradial symmetry only lanes passing through the oral-aboral axis will produce
mirrored halves. E.g Sea walnut
4. Bilateral symmetry applies to animals that can be divided along a sagittal plane into
two mirrored portions-right and left halves. E.g Tapeworm
Learning
University 2
Classification and Phylogeny
1. Monophyletic group is a group that includes the most recent common ancestor of a
group of organisms, and all of its descendants
2. plesiomorphic (plƒ sƒ-‰-m|r k). An ancestral condition of a variable character
ZOL1501 Exam Prep
1
, Prepare by Spirogyra
23 May 2019
3. parsimony (pär s‰-m|-nƒ) (L. parsus, to spare). A general methodological principle
that the simplest hypothesis capable of explaining observations is the best working
hypothesis and should be tested rst before investigating more complex hypotheses.
Learning Unit 3
Protozoan groups and single celled
organisms.
Give a detailed description of different kinds of pseudopodia encountered in protozoans
1. •Lobopodia are large blunt-tipped extensions of the cell body containing both
ectoplasm and endoplasm.
2. • Filipodia are this and sharply pointed extensions usually branching and
containing only ectoplasm.
3. • Rhizopodia are branched filamentous psedopodia made by some amebas.
4. • Reticolopodia are branched filaments that merge to form a netlike structure
and rejoin extensively.
5. • Axopodia are thin pointed psedopodia that contains a central longitudinal
filament of microtubules. The microtubules are arranged in a definite spiral or
geometrical array, depending on the species, and constitute the axoneme of the
axopod
Give an overview of a body plan of protozoans
‣ Protozoans are unicellular eukaryotes
‣ Have the nucleus enclosed in a membrane
‣ In Protozoa other than ciliates, the nucleus is vesicular, with scattered chromatin giving a
diffuse appearance to the nucleus, all nuclei in an individual appear alike.
‣ One type of vesicular nucleus contains a more or less central body, called endosome or
karyosome.
‣ Endosome lacks DNA is the parasitic amoebas and trypanosomes.
‣ In the phylum aplicomplexa, on the other hand the vesicular nucleus has one or more
nucleoli that contains DNA.
ZOL1501 Exam Prep
1
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