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2021 WAEC Biology Theory A sample of human blood was put in a test tube and allowed to spin...

Biology
WAEC 2021

A sample of human blood was put in a test tube and allowed to spin in a centrifuge. The components of the blood sample were clearly separated.
(a) List the four main components of blood that would be in the test tube.
(b) Name the component of the blood that: (i) would form the top layer in the test tube, (ii) destroys pathogens; (iii) is biconcave in shape (iv) would be relatively low in a haemophilic condition (v) is produced in the bone marrow: (vi) is a thrombocyte; (vii) is nucleated.
(c) Mention three chemical substances transported by the blood component named in 1(b)(i).
(d) List four diseases associated with blood.
(e) Explain briefly why a disease of the blood could be dangerous.

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Explanation

(a) Components of Blood: -(Blood) Plasma-Platelets(Thrombocytes) - White blood cells/Leucocytes - Red blood cells/erythrocytes.
(b) Name or Component of Blood that: (i) forms top layer in the test tube: (Blood) Plasma. (ii) Destroys Pathogens: White Blood Cells/Leucocytes (iii) Is Biconcave in shape: Red Blood Cells/Erythrocytes (iv) Would be relatively low in a Haemophilic condition: Platelets(Thrombocytes) (v) is produced in the bone marrow: - platelets (thrombocytes); - white blood cells/Erythrocytes; - Red blood cells/leucocytes cells/erythrocytes. (vi) Is a Thrombocyte: Platelets (vii) Is Nucleated: White Blood Cells/Leucocytes.
(c) Chemical Substances Transported by the Blood Component Named in 1(b)(i) Blood Plasma: -Thyroxine/Adrenaline/Insulin/Progesterone/Hormones. (Digested) food substances/Nutrients/Glucose Amino acids/Any correctly named digested food substances.-Antibodies/Antigens. -Oxygen/carbon(IV) oxide/dissolved gases.-Toxins -Mineral salts/salt /magnesium/copper/potassium/zinc -Urea/uric acid -Water -Vitamins
(d) Diseases Associated with Blood: -Anaemia/Anemia -Hepatitis -Sickle cell anaemia leukemia Luekaemia/Blood cancer.
(e) Reason a Disease that Attacks the Blood is Deadly: -The blood circulates throughout the body/it is a medium of transportation in the body.-It makes contact with major organs of the body and makes it easy for a disease to be deadly. -Blood disease could attack any component of blood and threatens life.


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WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
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Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709