Notes, summaries, assignments, exams, and problems for Biology

The Human Nervous System

Peripheral Nervous System (PNS)

Consists of cranial nerves and spinal nerves.

Central Nervous System (CNS)

Consists of the brain and spinal cord.

The Brain

• Cerebrum: Features left and right hemispheres with surface convolutions. It interprets sensory information and controls voluntary actions, emotions, and intellectual processes like thinking and speech.
• Cerebellum: Controls posture and balance, coordinating complex voluntary movements like walking.
• Brain Stem: Connects the brain and spinal cord, controlling involuntary actions such as heartbeat, breathing, body temperature, and sleep.

Spinal Cord

A column of nerve tissue protected by the spinal column. It connects the brain to the PNS, transmits nerve impulses, and controls... Continue reading "Human Nervous System: CNS and PNS Functions Explained" »

Organisation and Composition of Life

Levels of Organisation

Abiotic (Non-living) Levels

• Atom Level
• Molecule Level
• Macromolecule Level

Biotic (Living) Levels

• Organelle Level: e.g., Mitochondria
• Cellular Level: The fundamental unit of life
• Multicellular Level:
  • Tissue Sublevel
  • Organ Sublevel
  • Organ System Sublevel

Composition of Matter

• Primary Bioelements: Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur, Phosphorus (CHONSP)
• Secondary Bioelements: e.g., Calcium, Sodium
• Trace Bioelements: e.g., Iron, Zinc

The Building Blocks of Life

Cell Characteristics

Structure and Functions

• Cell Membrane: Surrounds, protects, and regulates the transfer of substances.
• Cytoplasm with Organelles: Carries out vital cellular functions.
• Genetic Material: Contains the instructions for life.

Cell

Deoxyribonucleic acid, or DNA, is a molecule that contains the instructions an organism needs to develop, live, and reproduce. These instructions are found inside every cell and are passed down from parents to their children.

Structure of DNA

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G), and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code. Human DNA has around 3 billion bases, and more than 99 percent of those bases are the same in all people, according to the U.S. National Library of Medicine (NLM).

Similar to the way the order of letters in... Continue reading "DNA Structure, Transcription, and Translation Explained" »

TRIMS 2

• 1) Which term describes an animal? All of the above
• 2) Swiss scientist who first described and named organisms with binomial nomenclature: Gaspard Bauhin
• 3) Developed a two-name system: Carl Linnaeus
• 4) Characteristics that appear in recent parts of a lineage but not in older members: Derived character
• 5) Classification based on common ancestry: Cladistics
• 6) Molecules that use mutation rates to study evolution: mtRNA
• 7) American ecologist who classified a fifth kingdom: Fungi
• 8) Discovered two genetically different groups: rRNA
• 9) Thick cell wall without outer membranes: Gram-positive
• 10) Which are insects? Beetles, roaches, termites
• 12) What are jellyfish? All of the above
• 13) Taenia, Toxocara, annelids first opening: Mouth
• 14) Soft, parasitic,

Organs and Organ Systems

Organs

Organs are complex structures composed of various types of tissue. They perform single or similar functions.

Organ Transplant

Organ transplant is the replacement of a damaged organ or tissue. A common problem is rejection.

Organ Systems

• Nutrition:
  • Digestive system: Digests food and absorbs nutrients.
  • Respiratory system: Exchanges O2 and CO2.
  • Circulatory system: Transports substances throughout the body.
  • Excretory system: Removes metabolic waste, such as urine.
• Interaction:
  • Nervous system: Receives stimuli and sends instructions.
  • Endocrine system: Produces hormones.
  • Locomotive system: Enables movement and provides protection.
• Reproduction:
  • Reproductive system: Creates new life.

Health and Illness

Concept of Health

Health is a state... Continue reading "Human Body: Organs, Systems, Health, and Disease" »

Phospholipid molecules form a bilayer - phospholipids are fluid and move laterally

Peripheral proteins are bound to either the inner or outer surface of the membrane

Integral proteins - permeate the surface of the membrane

The membrane is a fluid mosaic of phospholipids and proteins

Proteins can move laterally along membrane

Diffusion is the movement of particles from a region of high concentration to a region of low concentration, and is the result of the random motion of particles.

Facilitated diffusion is similar to simple diffusion, except that it requires channel proteins or carrier proteins, which are specific to the molecules being transported across the plasma membrane from high concentration to low concentration.

Osmosis is the passive movement... Continue reading "Cell Membrane Structure and Function" »

Fibra:Fiber is a complex carbohydrate of plant origin. Humans
cannot digest fiber or use it as a source of energy or
matter, but it is nonetheless essential for the functioning
of the digestive system.

Nutrients:Organic nutrients: are complex molecules produced by

Inorganic nutrients: are simple molecules that can be
found in living organisms, but have not been produced by
them. These nutrients are essential to your body but do
not supply any energy.
○ Minerals (such as calcium and sodium)
○ Water
○ Oxygen

Vitamins:Vitamins are organic components that the body either
cannot produce or produces only in insufficient
quantities.
● These must be obtained from food.
● All vitamins are needed in small quantities and they are
essential for regulating many... Continue reading "Where is cellobiose found in living organisms" »

Homeostasis and Environmental Response

All living things interact with their environment, including their surroundings and other organisms.

The environment is constantly changing. To survive and reproduce, living organisms must detect these changes and respond appropriately.

Responding to Stimuli

1. A stimulus is detected by receptors (structures or organs).
2. The stimulus is relayed to coordination systems, which interpret the signal and produce a response.
3. The organism responds using effectors (organs or structures).

Maintaining Internal Balance

To survive, living organisms must regulate their internal conditions.

Examples of internal conditions include temperature, water content, and concentrations of mineral salts and glucose in the blood.

Changes in... Continue reading "Homeostasis and Stimuli in Living Organisms" »

Blood: Composition and Vital Functions

Blood Composition

• Blood Plasma: The liquid component of blood.
• Blood Cells:
  • Red Blood Cells (Erythrocytes): Primarily responsible for oxygen transport.
  • White Blood Cells (Leukocytes): Key components of the body's immune and defense system.
  • Platelets: Essential for blood clotting and preventing excessive bleeding.

Key Functions of Blood

Blood serves as an effective transport system for various substances throughout the body:

• Oxygen Transport: Carries oxygen gas, primarily bound to hemoglobin. When hemoglobin is highly saturated with oxygen, it is called oxyhemoglobin.
• Nutrient and Waste Transport: Moves nutrients to cells and carries metabolic waste products away for excretion.
• Heat Distribution: Helps regulate and

Heart Anatomy and Function

Chambers and Valves

The heart is a muscular, hollow organ divided into four chambers:

• Upper Chambers (Atria): Left atrium and right atrium.
• Lower Chambers (Ventricles): Left ventricle and right ventricle.

Between the atrium and ventricle, the atrioventricular valve allows blood flow from the atrium to the ventricle but prevents backflow. The valve between the left atrium and ventricle is bicuspid, while the valve between the right atrium and ventricle is tricuspid.

Blood Circulation

Cardiac Cycle

• Atrial Systole: Atria contract, pumping blood into the ventricles through open atrioventricular valves.
• Ventricular Systole: Ventricles contract, sigmoid valves open, and blood flows into the pulmonary artery and aorta. Atrioventricular