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

Human Reproduction: Fundamental Processes

Human reproduction is sexual, meaning that both the mother and father contribute genetic material to their offspring via gametes. Offspring will have a mix of their parents' characteristics, and each person obtains their own unique genetic make-up.

The female gametes, ovules, and the male gametes, sperm, fuse together in the process called fertilisation, inside the female reproductive system, to form a zygote.

The embryo develops from the zygote inside the mother's uterus, undergoing repeated cell divisions. The new cells created specialise to form tissues and organs.

Sexual Characteristics and Puberty

Boys and girls are born with different reproductive organs, which constitute the so-called primary sexual

All cells in your body are surrounded by a liquid environment. They depend on it to stay alive. The internal environment is made up of the interstitial fluid and the circulating fluids. Lymph is the fluid that flows through the lymphatic vessels. It is formed from the remaining interstitial fluid. Blood is the fluid in charge of transporting substances through the inside of blood vessels. Interstitial fluid is the fluid that surrounds every cell. Cells extract nutrients, oxygen and release into the waste and carbon dioxide produced in cell metabolism. The circulatory system connects the system involved in the nutrition function with the interstitial fluid that surrounds the cells in the body. It has 2 systems: the cardiovascular system through... Continue reading "Understanding the Circulatory System and Its Functions" »

Organization of Life

Atoms: smallest unit of an element that still retains the element's properties.

Molecules: two or more joined atoms of the same or different elements.

Cell: smallest unit of life that can live and reproduce on its own or as part of a multicellular organism.

Multicellular organisms: made of specialized, interdependent cells that are often organized into:

• Tissues
• Organs
• Organ systems

Population: consists of individuals of the same species in a specified area.

Community: consists of all populations occupying the same area.

Ecosystem: a community interacting with its physical and chemical environment.

Biosphere: includes all regions of Earth's atmosphere, waters, and land where we find living organisms.

DNA is inherited.

Inheritance: an... Continue reading "Organization of Life and Enzymes: An Overview" »

The Digestive System

Liver

The liver, the largest internal organ, contains ducts called hepatocytes. These hepatocytes collect bile secreted by liver cells. The liver plays a crucial role in the metabolism of carbohydrates, lipids, and proteins.

Gallbladder

The gallbladder is a pear-shaped structure located under the liver. Its primary function is to store bile.

Pancreas

The pancreas is a long, narrow gland with two ducts, located on the left side of the abdomen.

Small Intestine

The small intestine starts at the pylorus and ends at the ileocaecal valve, where it joins the large intestine. It has two main parts:

• Duodenum: Secretes bile and pancreatic juice into this section.
• Jejunum and Ileum: Form the rest of the intestine. The small intestine is covered

Energy: Capacity for Change

Potential Energy: Stored energy.

Kinetic Energy: Energy from motion.

Conservation of Energy: Energy cannot be created or destroyed.

Heat: A usually random form of energy.

Entropy: A measure of disorder or randomness.

Chemical Energy: Energy stored in chemical bonds, such as food.

ATP Molecule

Draw a molecule of ATP: Adenosine-P-P-P

Metabolism

Metabolism: The total of all chemical reactions in an organism, requiring enzymes.

ATP and Cellular Work

ATP energy helps cells perform three types of work:

1. Chemical: Assists chemical reactions.
2. Transport: Performs transport work.
3. Mechanical: Moves muscle fibers, for example.

Enzyme Assistance

How do enzymes assist in chemical reactions?

1. Enzymes provide an active site specific to a substrate

Finger prick:

Nociceptors in the finger are stimulated by a mechanical stimuli beginning reflex. AP occurs through graded potentials called excitatory post synaptic potentials. As ESPS summate at axon hillock and surpass threshold AP is created. This happens when an influx of sodium depolarizes the cell, while potassium effluxes. At max influx, gates close.

Sodium potassium pump begins another AP. It goes down myelinated nerve which travels to spinal cord.

Chug water

The water increases blood pressure, which affects the systems.

Circulatory System:

Increased water changes the blood and osmotic condition. The main concern is sodium levels in the body. Since the cell is diluted in water, the cell must adjust to this. Swelling occurs in rnc and also

Properties of the Basilar Membrane

The basilar membrane has varying physical properties along its length:

• Base: Thick, stiff, and narrow (ideal for high frequencies).
• Apex: Thin, less stiff, and wide (ideal for low frequencies).

High frequencies do not move fluid effectively, whereas low frequencies do. Therefore, it is more efficient for high frequencies to cross the membrane early (at the base) and for low frequencies to cross later (at the apex).

Evidence for Active Amplification in the Inner Ear

Experiments measuring sound energy input and output provide evidence for active amplification within the inner ear:

1. Sound energy output was observed to be higher than sound energy input, suggesting an active amplification process.

Outer hair cells are likely... Continue reading "Basilar Membrane Properties and Auditory Signal Processing" »

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" »

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" »