Lesson Notes By Weeks and Term v4 - JHS 2
LIFE CYCLE OF ORGANISMS
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LIFE CYCLE OF ORGANISMS
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Subject: Science
Class: JHS 2
Term: 1st Term
Week: 9
Grade code: B8.2.2.1.2
Strand code: 2
Sub-strand code: 2
Content standard code: B8.2.2.1
Indicator code: B8.2.2.1.2
Theme: CYCLES
Subtheme: LIFE CYCLE OF ORGANISMS
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In Ghana, malaria is one of the commonest illnesses affecting children and adults. Many learners have seen a family member miss school or work because of fever, chills and weakness. Malaria is closely linked to the life cycle of the female *Anopheles* mosquito and the life cycle of the malaria parasite (*Plasmodium*). Understanding the impact of the female *Anopheles* mosquito helps learners make informed decisions to protect themselves, their families and their communities.
A. Key Terms Organism: A living thing (e.g., mosquito, human, parasite). Life cycle: The stages an organism passes through from birth to adulthood and reproduction. Vector: An organism that carries and transmits a disease-causing organism from one host to another. Parasite: An organism that lives in or on another organism (host) and causes harm. Malaria: A disease caused by *Plasmodium* parasites, transmitted to humans through bites of infected female *Anopheles* mosquitoes. Host: An organism that harbours a parasite (humans are hosts for *Plasmodium*). B. The Female *Anopheles* Mosquito and Why It Matters Only the female mosquito bites humans. Female mosquitoes need blood to get proteins for egg development. Male mosquitoes feed mainly on plant juices/nectar and do not usually bite humans. Female *Anopheles* is the main malaria vector. When a female *Anopheles* bites a person who has malaria parasites in their blood, it can pick up the parasites. Later, when it bites another person, it can inject the parasites into that person’s blood. Common behaviour linked to malaria transmission Many *Anopheles* mosquitoes bite from evening to dawn (night biting). They often breed in clean or relatively clean stagnant water (e.g., puddles, hoof prints, rice fields, water collected in containers around homes).
> Important point for learners: Not every mosquito transmits malaria. Malaria transmission is mainly by female *Anopheles* mosquitoes carrying Plasmodium. C. How *Plasmodium* is Transmitted (Step-by-step) This is the key “life cycle link” between mosquito and humans. Step 1: Infected human → mosquito A person with malaria has *Plasmodium* in their blood. A female *Anopheles* bites the infected person and sucks blood. The mosquito takes in the parasite (especially the forms that can develop inside the mosquito). Step 2: Parasite develops inside mosquito Inside the mosquito, *Plasmodium* undergoes development (changes into forms that can infect humans). The parasite eventually moves to the mosquito’s salivary glands. Step 3: Infected mosquito → new human The same mosquito bites another person. While biting, the mosquito injects saliva to prevent blood clotting. The saliva contains *Plasmodium* which enters the person’s bloodstream, leading to malaria infection. D. Impact of the Female *Anopheles* Mosquito on Humans (Main Focus) Because the female *Anopheles* transmits malaria, its impact on humans is largely the impact of malaria on individuals, families, and the nation. Health impacts (on the body) Fever, chills, sweating Headache, body pains, weakness Vomiting and loss of appetite Anaemia (low blood level) especially in children and pregnant women Severe malaria can cause: convulsions, unconsciousness (cerebral malaria) organ failure death (especially in young children if not treated early) Impact on education (learners and schools) Absenteeism: learners miss classes due to sickness or hospital visits. Poor concentration and low performance due to weakness and repeated illness. Teachers may also be absent, affecting teaching and learning. Economic impacts (family and national level) Money spent on: hospital/clinic bills, medicines, transport prevention items (nets, sprays) Loss of productivity: parents miss work or farming days to care for sick family members reduced income for households National impact: increased health expenditure reduced workforce productivity Social and community impacts Increased burden on caregivers (often mothers/guardians). Stress and anxiety in families. In severe cases, loss of life affects family stability. E. Controlling Malaria in Ghana (Solutions) Control must target both the mosquito life cycle and human exposure. Prevent mosquito breeding (environmental management) Drain stagnant water around homes and schools. Clear choked gutters. Cover water storage containers. Properly dispose of empty cans, tyres, and plastics that collect water. Fill potholes/ground depressions where water collects. Prevent mosquito bites (personal protection) Sleep under Insecticide-Treated Nets (ITNs) every night. Use window/door screens and close doors early. Wear long sleeves/trousers in the evening where possible. Use mosquito repellents when necessary. Kill mosquitoes (vector control) Indoor residual spraying (where available). Use approved insecticide sprays/coils carefully and safely. Early diagnosis and treatment (reduce parasite reservoir) Go to the clinic for testing when symptoms appear. Complete prescribed treatment (do not stop halfway). This reduces the number of infected people mosquitoes can pick parasites from. Community education and collaboration Community clean-up exercises. Health talks at school, churches/mosques, and community meetings. Reporting and supporting local sanitation efforts.
Cross-cutting competencies (NaCCA alignment): Critical Thinking & Problem Solving (CP): Identify breeding sites and plan solutions. Communication & Collaboration (CC): Explain prevention steps clearly; work in groups for clean-up plans. Digital Literacy (DL): Use phone/internet (if available) to find Ghana Health Service malaria prevention messages. Creativity & Innovation (CI): Design posters, jingles, or simple community campaigns.
Guided Practice (With Solutions) Question 1 (Basic understanding) Explain why only the female *Anopheles* mosquito is mainly responsible for spreading malaria.