1. The tiny contractile units within muscle cells are called:

A. Myocytes
B. Myofibrils
C. Sarcomeres
D. Tendons

Correct answer: C

Rationale: The correct answer is C: Sarcomeres. Sarcomeres are the basic contractile units within muscle cells. They are made up of overlapping filaments of actin and myosin proteins, which slide past each other during muscle contraction, resulting in muscle movement. Myocytes (A) are muscle cells, myofibrils (B) are cylindrical structures within muscle fibers composed of sarcomeres, and tendons (D) are tough bands of connective tissue that connect muscle to bone. Therefore, sarcomeres are specifically responsible for muscle contraction within muscle cells.

2. The microscopic functional unit of the kidney responsible for filtering blood is the:

A. Ureter
B. Nephron
C. Renal pelvis
D. Bladder

Correct answer: B

Rationale: The correct answer is B: Nephron. The nephron is the microscopic functional unit of the kidney responsible for filtering blood and producing urine. It consists of the glomerulus, Bowman's capsule, proximal convoluted tubule, loop of Henle, and distal convoluted tubule. The other options, A: Ureter, C: Renal pelvis, and D: Bladder, are incorrect as they are not parts of the nephron but rather other structures involved in the urinary system. The ureter is a tube that carries urine from the kidneys to the bladder, the renal pelvis is a funnel-shaped structure in the kidney that collects urine, and the bladder stores urine before it is excreted from the body.

3. What are enzymes?

A. Building blocks of muscle
B. Biological catalysts
C. Energy source
D. Antibodies

Correct answer: B

Rationale: Enzymes are proteins that speed up chemical reactions in our cells. They act like tiny factories, fitting specific molecules (substrates) into their active site to facilitate reactions.

4. What property of a substance refers to its ability to be drawn into thin wires?

A. Conductivity
B. Ductility
C. Viscosity
D. Malleability

Correct answer: b

Rationale: Ductility refers to a substance's ability to be drawn into thin wires without breaking.

5. The pH scale is used to indicate the concentration of:

A. Oxygen
B. Hydrogen ions
C. Salts
D. Sugar molecules

Correct answer: A

Rationale: The pH scale measures the concentration of hydrogen ions in a solution, indicating acidity or basicity.

6. Classifications of human tissues exclude:

A. Epithelial tissue
B. Nervous tissue
C. Adipose tissue (a specialized form of connective tissue)
D. Bony tissue

Correct answer: D

Rationale: The correct answer is D: 'Bony tissue.' Classifications of human tissues typically include four main types: epithelial, connective, muscular, and nervous tissue. Bony tissue, also known as osseous tissue, is a specialized form of connective tissue that forms bones in the skeletal system. While bony tissue is an essential component of the human body, it is not typically categorized separately as a distinct tissue type in general tissue classifications. Therefore, it is the exception from the list provided in the question, making it the correct answer.