(a) Explain the following terms:
(i) disease
(ii) symptoms of diseases.
(b)(i) List two physical and two chemical barriers that prevent pathogens from penetrating the body of an organism.
(ii) Explain how vaccination protects the body from contracting infectious diseases.
(c) Distinguish between an antibody and a antigen.
(d) Name the causative agents of:
(i) Malaria
(ii) Cholera
(iii) AIDS.
Explanation
(a)(i) Disease: A condition in which the normal functions of an organism/part of the body/cell/tissue/organ is impaired/disturbed.
(ii) Symptom: Any observable effect on an organism: Caused by the presence and irritation of a disease-causing agent/pathogen.
(b)(i) Physical barriers:
(i) Skin
(ii) Hairs
(iii) Cuticle
(iv) Epidermis
(v) Bark
(vi) Cell wall lining.
Chemical barriers:
(i) Mucus
(ii) Saliva
(iii) Tears
(iv) Gastric/ HCL and intestinal secretions
(v) Phenolic compound
(vi) Gums
(vii) Tannins
(viii) Wax
(ix) Oily secretions! sebum
(ii) How vaccination protects the body: The vaccine/attenuated pathogen is administered into the body. The body responds by producing copious antibodies. The next time the body is exposed to the same antigen/infection/pathogen antigen, the memory cells allow a more rapid and heightened/vigorous response to antibody production. Protection of the body against future infections.
(c) Differences between antibodies and antigens
(I) Antibodies is a protein molecule. Antigens May not be a protein molecule
(ii) Antibodies is Produced in response to a particular foreign substance/antigen while antigens Stimulates formation of antibodies
(iii) Antibodies Usually found in the plasma fluid of the blood,antigens are Usually produced in/introduced into the body.
(iv) Antibodies are Protective in functions, antigens Leads to an immune response/immunity.
(d) Causative Agent:
(i) Malaria: Plasmodium vivax/Plasmodium/malaria/species
(ii) Cholera: Vibrio cholera.
(ii) AIDS: Human Immuno-deficiency virus/HIV