A. Make an annotated diagram of a named cestode (measuring 10-12cm). 1. B. Name the causal agent for the following diseases: (i) amoebiasis (ii) malaria (iii) taeniasis (iv) liver rot (v) loiasis. 1.

Here are the answers to your questions.

SECTION A

1. A. Make an annotated diagram of a named cestode (measuring 10-12cm).
A diagram cannot be provided in this format.
An annotated diagram of a cestode (e.g., Taenia solium or Taenia saginata) measuring 10-12 cm would typically include:

• Scolex: The head region, equipped with suckers (and hooks in Taenia solium) for attachment to the host's intestinal wall.
• Neck: A short, unsegmented region immediately posterior to the scolex, from which new proglottids are budded.
• Strobila: The main body, composed of a chain of segments called proglottids.
  • Immature proglottids: Nearest the neck, without developed reproductive organs.
  • Mature proglottids: In the middle, containing fully developed male and female reproductive organs.
  • Gravid proglottids: Furthest from the neck, filled with thousands of fertilized eggs.

1. B. Name the causal agent for the following diseases:

• (i) amoebiasis: Entamoeba histolytica
• (ii) malaria: Plasmodium species (e.g., Plasmodium falciparum, Plasmodium vivax)
• (iii) taeniasis: Taenia species (e.g., Taenia solium, Taenia saginata)
• (iv) liver rot: Fasciola hepatica
• (v) loiasis: Loa loa

1. C. State the differences between Fasciola hepatica and Schistosoma haematobium.

Feature	Fasciola hepatica (Liver Fluke)	Schistosoma haematobium (Blood Fluke)
Class	Trematoda (Digenea)	Trematoda (Digenea)
Habitat in Host	Bile ducts of liver	Venous plexuses of the urinary bladder
Body Shape	Leaf-like, broad and flattened	Elongated, cylindrical, males have a gynecophoric canal for females
Sexes	Hermaphroditic (monoecious)	Dioecious (separate male and female worms)
Oral Sucker	Present	Present
Ventral Sucker	Present (acetabulum)	Present (acetabulum)
Eggs	Large, operculated, unembryonated when passed in feces	Spined (terminal spine), unoperculated, embryonated when passed in urine
Intermediate Host	Freshwater snails (e.g., Lymnaea species)	Freshwater snails (e.g., Bulinus species)
Infective Stage	Metacercariae on aquatic vegetation	Cercariae in water
Disease	Fascioliasis (liver rot)	Urogenital schistosomiasis

2. A. Outline the three (3) structural modifications that adapted intestinal worms to parasitic life.

1. Attachment Organs: Presence of specialized structures like suckers, hooks, or spines (e.g., scolex of tapeworms) to firmly attach to the host's intestinal wall and resist peristalsis.
2. Protective Cuticle: A thick, tough, and chemically resistant cuticle or tegument covering the body surface, which protects the worm from the host's digestive enzymes and immune responses.
3. Reduced Digestive System/High Absorption: Many intestinal parasites have a reduced or absent digestive system (e.g., tapeworms lack a mouth and anus). Instead, they absorb pre-digested nutrients directly through their body surface, saving energy.

2. B. Contrast between trematode, cestode and nematode (in a tabular form).

Feature	Trematode (Flukes)	Cestode (Tapeworms)	Nematode (Roundworms)
Body Shape	Leaf-like or elongated, flattened	Ribbon-like, segmented	Cylindrical, unsegmented
Body Cavity	Acoelomate (no body cavity)	Acoelomate	Pseudocoelomate (false body cavity)
Digestive System	Incomplete (mouth, pharynx, branched gut, no anus)	Absent (nutrients absorbed through tegument)	Complete (mouth, pharynx, intestine, anus)
Segmentation	Unsegmented	Segmented (proglottids)	Unsegmented
Sexes	Mostly hermaphroditic (some dioecious, e.g., Schistosoma)	Hermaphroditic	Dioecious (separate male and female)
Attachment	Oral and ventral suckers	Scolex with suckers and/or hooks	Lips, teeth, dentigerous plates, or suckers around mouth
Life Cycle	Complex, usually 2 intermediate hosts	Complex, usually 1 or 2 intermediate hosts	Simple or complex, direct or indirect
Examples	Fasciola hepatica, Schistosoma spp.	Taenia solium, Echinococcus granulosus	Ascaris lumbricoides, Enterobius vermicularis

2. C. Define the following terms:

• Parasitism: A symbiotic relationship where one organism, the parasite, lives on or in another organism, the host, and benefits by deriving nutrients at the host's expense, often causing harm.
• Commensalism: A symbiotic relationship where one organism, the commensal, benefits from the association, while the other organism, the host, is neither significantly harmed nor benefited.
• Symbiosis: A close and long-term biological interaction between two different biological organisms, which can be mutualistic, commensalistic, or parasitic.
• Vector: An organism, typically an arthropod (like a mosquito or tick), that transmits a pathogen from one host to another.

3. A. What is a pest?
A pest is any organism (animal, plant, or microorganism) that causes damage or annoyance to humans, their crops, livestock, property, or environment.

3. B. Highlight five agricultural and medical pests that you know.

• Agricultural Pests:
  1. Locusts (e.g., Schistocerca gregaria) - devour crops.
  2. Aphids (e.g., Myzus persicae) - suck plant sap, transmit viruses.
  3. Weevils (e.g., Sitophilus oryzae) - infest stored grains.
  4. Rats (e.g., Rattus rattus) - consume and contaminate crops and stored food.
  5. Fall Armyworm (Spodoptera frugiperda) - larvae feed on maize and other crops.
• Medical Pests:
  1. Mosquitoes (e.g., Anopheles spp.) - transmit malaria, dengue, etc.
  2. Tsetse flies (Glossina spp.) - transmit African trypanosomiasis (sleeping sickness).
  3. Ticks (e.g., Ixodes scapularis) - transmit Lyme disease.
  4. Fleas (e.g., Xenopsylla cheopis) - transmit plague.
  5. Houseflies (Musca domestica) - mechanically transmit various pathogens.

3. C. Write short notes on the following:

• (i) Biological control of pest: This is a method of pest control that uses natural enemies (predators, parasites, pathogens) to reduce pest populations. It is an environmentally friendly approach that aims to maintain a balance in the ecosystem rather than eradicate pests completely. For example, introducing ladybugs to control aphid infestations.
• (ii) Chemical control of pest: This involves the use of synthetic or naturally derived chemical substances (pesticides, herbicides, insecticides) to kill, repel, or inhibit the growth of pests. While effective for rapid pest reduction, it can have adverse effects on non-target organisms, human health, and the environment. For example, spraying DDT to kill mosquitoes.

SECTION B

1. A. What is microbiological growth media?
Microbiological growth media (or culture media) are nutrient-rich formulations, either liquid (broth) or solid (agar), designed to support the growth, survival, and multiplication of microorganisms in a laboratory setting. They provide essential nutrients, energy sources, and appropriate physical conditions (pH, osmotic pressure) for microbial cultivation.

1. B. A lab Technician was directed to prepare eight (8) glass petri dishes of nutrient agar (NA) for a microbiology practical section. If the manufacturer instructed that 28.0g should be dissolved in 1000ml of distilled water. Calculate the amount in grams of nutrient agar used.
To calculate the amount of nutrient agar used, we need to determine the total volume of agar needed for 8 petri dishes. A standard petri dish typically holds about $15 \text{ mL}$ to $20 \text{ mL}$ of agar. Let's assume $15 \text{ mL}$ per petri dish for this calculation.

Step 1: Calculate the total volume of agar needed.

$$\text{Total volume} = \text{Number of petri dishes} \times \text{Volume per petri dish}$$ $$\text{Total volume} = 8 \text{ dishes} \times 15 \text{ mL/dish} = 120 \text{ mL}$$

Step 2: Use the manufacturer's instruction to find the amount of NA for this volume.
The manufacturer instructs $28.0 \text{ g}$ of NA for $1000 \text{ mL}$ of water.

$$\text{Amount of NA per mL} = \frac{28.0 \text{ g}}{1000 \text{ mL}} = 0.028 \text{ g/mL}$$

Step 3: Calculate the total amount of NA needed for $120 \text{ mL}$.

$$\text{Amount of NA used} = \text{Amount of NA per mL} \times \text{Total volume}$$ $$\text{Amount of NA used} = 0.028 \text{ g/mL} \times 120 \text{ mL}$$ $$$$