Pepsin is the main enzyme that digests proteins in the acidic environment of the stomach.

Uric acid is the main excretory product of purine metabolism in humans.

Climate is the main factor that determines the type of ecosystem, influencing temperature and precipitation patterns.

Alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs, making them essential for respiration.

Antibodies are proteins produced by the immune system to identify and neutralize pathogens such as bacteria and viruses.

Cartilage provides support and flexibility to various structures in the body, such as joints and the rib cage.

Decomposers recycle nutrients by breaking down dead organic matter, returning essential nutrients to the soil.

Ligaments connect bone to bone, providing stability to joints.

Phloem is responsible for the transport of food (sugars) produced during photosynthesis from leaves to other parts of the plant.

Plasma is the liquid component of blood that carries nutrients, hormones, and waste products throughout the body.

Producers, such as plants, produce energy through photosynthesis, forming the base of the food chain.

Sepals protect the flower bud before it opens.

Skeletal muscle tissue is responsible for voluntary movements of the body, allowing for locomotion and manipulation.

Stratified squamous epithelium primarily functions in protection against abrasion and pathogens.

Surfactant reduces surface tension in the alveoli, preventing their collapse and making it easier for the lungs to expand during inhalation.

The anther is the part of the stamen that produces and contains pollen grains.

The cell wall provides protection and structural support to plant cells, maintaining their shape.

Gastric acid activates digestive enzymes, particularly pepsinogen to pepsin, and helps in protein digestion.

Gastric juice contains hydrochloric acid and pepsin, which are essential for the digestion of proteins.

The immune system's primary function is to protect the body against pathogens and diseases.

Stomata are small openings on the leaf surface that facilitate gas exchange, allowing carbon dioxide in and oxygen out.

The primary function of the male reproductive system is to produce sperm for reproduction.

The nephron is the functional unit of the kidney responsible for the filtration of blood and the formation of urine.

The nucleus stores the cell's genetic information and coordinates activities such as growth, metabolism, and reproduction.

The nucleus stores genetic information and controls cellular activities by regulating gene expression.

The pancreas produces digestive enzymes that help in the digestion of carbohydrates, proteins, and fats.

The renal pelvis collects urine from the collecting ducts and transports it to the ureter.

The main function of the respiratory system is gas exchange, specifically the intake of oxygen and the removal of carbon dioxide.

The root system primarily anchors the plant and absorbs water and nutrients from the soil.

The main function of the seminal vesicles is the production of seminal fluid, which nourishes and helps transport sperm.