ZOO201 Midterm Questions January 2022 by Safdar Rind

ZOO201 MIDTERM FALL2022 ZOO 201/20.1.22/8:30 AM *Arthropods/Annelids difference* 5marks

Arthropods are invertebrate animals that possess a segmented body, an exoskeleton, and paired appendages. Whereas, annelids are another group of invertebrates that are segmented worms by transverse rings. Though arthropods have an exoskeleton, annelids do not. Furthermore, arthropods have an open circulatory system while annelids have a closed circulatory system. Moreover, arthropods have a chitinous cuticle while annelids have a collagenous cuticle. Insects, crustaceans, arachnids are several groups of arthropods while earthworms, ragworms, and leeches are some groups of annelids. Thus, this summarizes the difference between arthropods and annelids.

*Body wall of turbellarian*5marks

Body wall: A basement membrane that separates the epidermis from mesodermally derived tissues. An outer layer of circular muscles and inner layer of longitudinal muscle lie beneath the basement membrane. The innermost layer is endodermis that comprises the digestive cavity. Rhabdites a protective mucus sheath around the body possibly in response to attempted predation or desiccation. Adhesive glands attract part of turbellaria to the substrate. Releaser glands release the enzyme that dissolved the attachment. Locomotion: They move using cilia using muscular undulation.

Digestion and Nutrition: Most turbellarians are carnivores, some are herbivores. Food digestion is extracellular and intracellular.

*monoecious/diecious species* 3 marks

Dioecious species are either male or female. Each individual, when it produces reproductive structures, produces only male or female structures.

*Function of pellicle in protozoa* 2 marks

Most protozoans are enclosed by a skeletal structure known as the pellicle consisting of the plasma membrane and underlying cytoskeleton (with additional membranes, microtubules, microfilaments, or plates of cellulose or protein). The pellicle maintains the shape of the cell.

Define typhlosole 2 marks A dorsal fold of the luminal epithelium called the typhlosole substantially increases the surface area of the intestine. Tubular system 2marks Parasitic nematodes have a more advances system, called the tubular system that developed from the renette system. In this system, the renettes unite to form a large canal which opens outside through an excretory pore.

Long Q marks

Characteristics of phylum cnidaria include:

1. Radial or biradial symmetry
2. Diploblastic, tissue-level organization
3. Gastrovascular cavity
4. Gelatinous mesoglea between the epidermal and gastrodermal tissue

layers.

5. Nervous system in the form of a nerve net.
6. Specialized cells called cnidocytes, used in defense, feeding, and attachment.
7. Endocrine have hormones, secreted by

nervous system.

8. No circulatory system, use cellular diffusion and mesoglea.
9. Ciliated planula larva is found.
10. Members of the phylum Cnidarian (Gr. knide means nettle) possess radial or biradial symmetry.

Characteristics of deuterostomes:

Deuterostomes are also known as enterocoelomates because their coelom develops through enterocoely. There are three major clades of deuterostomes:

1. Chordata (vertebrates and their kin)
2. Echinodermata (starfish, sea urchins,

sea, cucumbers, etc.)

• 3. Hemichordata (acorn warms and graptolites). Extinct deuterostome groups may include the phylum Vetulicolia.

It is a sister clade of Protostomia, with which forms the Nephrozoa clade. Parasitic Nematoda show evolutionary adoption? Parasitic nematodes show a number of evolutionary adaptations to the way of their life. These adaptations are:

• 1. They have high reproductive potential.
• 2. Their life cycles increase the likelihood of transmission from one host to another.
• 3. They develop an enzyme resistant cuticle, resistant eggs, and encysted larvae.

Q No2 Difference between monophyletic, Diphyletic and polyphyletic?

• A fundamental question concerning animal origins is whether animals are;
• Monophyletic (derived from a single ancestor)
• Diphyletic (derived from two ancestors)
• Polyphyletic (derived from many ancestors).

Monophyletic:

The goal of animal systematics is to arrange animals into groups that reflect evolutionary relationships.

• Ideally, these groups should include a single ancestral species and all of its descendants.
• Such a group is called a monophyletic group.

Diphyletic: Some zoologists believe the animal kingdom to be at least diphyletic, with the porifera being derived separately from all other phyla.

• The similarity of poriferan choanocytes and choanoflagellates protists suggest evolutionary ties between these groups.

Polyphyletic: These groups have members that can be traced to separate ancestors.

What is spongocoel?

Ostia are the outer openings of porocytes and lead directly to a chamber called the spongocoel. It is a single, large, spacious central cavity in the sponge's body.

Define Determinate cleavage?

Determinate cleavage: A second characteristic common to many protostomes is that early cleavage is determinate.

• Determinate means that the fate the cells is established very early in development.

Q No Circulatory system in cephalopod:

Cephalopods have a closed circulatory system.

• Blood is confined to vessels throughout its circuit around the body.
• Capillary beds connect arteries and veins, and exchanges of gases, nutrients, and metabolic wastes occur across capillary walls.
• In addition to having a heart consisting of two auricles and one ventricle, cephalopods have contractile arteries

and structures called branchial hearts.