Year 8 Science Full Study Notes

Comprehensive study flashcards covering Year 8 Science topics including living systems, human anatomy, digestive/circulatory/respiratory/excretory systems, atomic structure, the periodic table, and energy transfers.

What are organs?

Organs are structures made of tissues that perform specific jobs, such as the heart pumping blood or lungs enabling breathing, which work together to form organ systems.

What is the role of an anatomist?

Anatomists are scientists who study how the body works by examining its structure (how parts are built) and function (what they do).

What are the four main types of tissue in the human body?

1. Epithelial (protects surfaces), 2. Connective (supports and binds tissues), 3. Muscle (contracts/relaxes for movement), and 4. Nervous (signal system from brain to muscles).

What is the primary function of the heart in the circulatory system?

The heart acts as the organ of circulation by pumping oxygenated blood throughout the body using muscle, valves, and blood vessels.

Describe the structure and function of the lungs.

Lungs are spongy organs with alveoli that function to take in $O_2$ and remove $CO_2$ as part of the respiratory system.

What is the specific goal of the digestive system?

To break LARGE INSOLUBLE food particles into SMALLER SOLUBLE parts that are able to be ABSORBED into the bloodstream.

What are the functions of the liver and gallbladder?

The liver produces bile to break down fat, and the gallbladder stores that bile.

What is the difference between the small and large intestines?

The small intestine is where food molecules are absorbed into the bloodstream, while the large intestine is where water from waste food is absorbed.

How do amylase, protease, and lipase differ in function?

Amylase (carbohydrase) breaks down starch into maltose and glucose; Protease breaks proteins into amino acids for growth and repair; Lipase breaks fats into fatty acids and glycerol.

Contrast the digestive tracts of herbivores and carnivores.

Herbivores have long intestines to extract nutrition from tough plants and flat teeth for grinding; carnivores have short intestines for quick meat breakdown and sharp canines for gripping prey.

How does Coeliac disease differ from gluten intolerance?

Coeliac disease is an autoimmune disorder where gluten triggers the immune system to flatten villi and damage the small intestine; gluten intolerance involves no immune attack or permanent damage but causes similar symptoms like bloating.

What is the difference between Crohn’s disease and Ulcerative Colitis?

Crohn’s disease can affect any part of the digestive tract with patchy inflammation through all gut wall layers; Ulcerative Colitis only affects the large intestine and rectum with continuous inflammation in the inner lining.

Describe the flow of blood through the heart during a heartbeat.

Blood flows into the atria as muscles relax; atria contract to push blood through valves into the ventricles; then ventricles contract to force blood out of the heart while valves close to prevent backflow.

What are the structural differences between arteries and veins?

Arteries have thick muscle and elastic fibres to carry blood away from the heart under pressure; veins have valves to prevent backflow and rely on body muscles to push blood towards the heart.

What are the specific functions of Red Blood Cells and White Blood Cells?

Red Blood Cells contain haemoglobin to carry oxygen; White Blood Cells include macrophages that 'eat' microorganisms and lymphocytes that make antibodies or antitoxins.

What are stents and statins used for?

Stents are metal wires used to push plaque outward to open narrowed arteries; statins are drugs that reduce cholesterol levels to slow fatty material deposition.

What are the advantages and disadvantages of mechanical valve replacement?

Advantages: Very strong and durable (can last a lifetime). Disadvantages: May damage red blood cells, requires lifetime anti-blood clotting drugs, and makes noise when operating.

List three adaptations of the alveoli for gas exchange.

1. Wall is one cell layer thick for short diffusion distance. 2. Copious blood supply for continuous oxygen absorption. 3. Millions of alveoli providing a large surface area.

What happens to the lungs in emphysema?

The walls between alveoli break down, reducing surface area for oxygen absorption, and the lungs lose elasticity, making it difficult to exhale.

What are the three distinct areas seen in a cut through a kidney?

The outer cortex, the middle medulla, and the inner pelvis (leading to the ureter).

What is the role of ADH in the excretory system?

Anti-diuretic hormone (ADH) regulates the amount of urine produced by the kidneys.

How is urea formed and why must it be excreted?

Urea is a toxic by-product of the liver breaking down excess amino acids (from proteins); it must be filtered by the kidneys and excreted as urine.

What are xylem and phloem cells?

Xylem cells transport water and minerals upward from roots to leaves in one direction; phloem cells transport sugars produced in leaves up and down the stem.

Who discovered the electron and developed the plum-pudding model?

JJ Tompson in 1898.

How did Dimitri Mendeleev organize his periodic table?

He arranged elements by increasing atomic mass and vertical groups, leaving gaps for undiscovered elements he predicted would fit.

Define ions, cations, and anions.

Ions are charged particles; cations are metals that lose electrons to become positive; anions are nonmetals that gain electrons to become negative.

What are the characteristics of Noble gases?

They are elements in group 8/0 (last column) and are VERY unreactive gases.

What is the formula for Kinetic Energy?

$KE = \frac{1}{2}mv^2$ where $m$ is mass in $kg$, $v$ is velocity in $m/s$, and $KE$ is kinetic energy in $J$.

What is the difference between energy transformation and energy transfer?

Energy transformation is the change from one form to another (e.g., chemical to kinetic); energy transfer is the movement of energy from one object to another without changing its form (e.g., heat moving from stove to pan).

What are the four components of a full scientific method described in the notes?

1. Hypothesis (prediction with evidence), 2. Graph (line or bar), 3. Table (recording data), and 4. Conclusion (confirming or rejecting hypothesis).