(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