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

Ecosystem Components and Definitions

An ecosystem is a system formed by different organisms (biocenosis), the environment, its physical and chemical characteristics (biotope), and the interactions that are established between them.

Environmental Factors and Biocenosis

Environmental factors are all the components of the ecosystem that have an impact on the biocenosis. They determine the distribution and composition of the biocenosis, the number of organisms present, and the adaptation of the organisms.

Abiotic Factors and Climatic Conditions

Abiotic factors include physical and chemical components such as temperature, water, and light. Climatic conditions form the large terrestrial ecosystems or biomes.

Biodiversity and Organism Adaptations

Organisms... Continue reading "Ecosystem Dynamics and Species Interactions" »

Impulse Transmission in the Nervous System

Impulse / nervous system: The stimulus is received and a depolarization takes place in the neuron membrane. The impulse travels along the axon; many axons are insulated by a substance called myelin. When the impulse arrives at the end of the axon it has to cross a gap called the synaptic cleft. Synaptic vesicles fuse with the membrane and release neurotransmitters, which pass to the dendrite of the next neuron. The message then goes to the nervous system and finally to the effectors.

Protection of the Central Nervous System

Protection of the CNS: The brain and the spinal cord are surrounded by three membranes called the meninges and by a liquid called the cerebrospinal fluid (líquido encefalorraquídeo)... Continue reading "Nervous System Function, Neuron Structure & Sense Organs" »

Infectious Disease

is caused by agents that have invaded the body

Pathogen

any agent that causes disease

Koch Postulates

rules for determining the cause of a disease

Mucous Membrane

epithelial tissue that protects the inferior surface of the body that might be exposed to pathogens

Inflammatory Response

events that suppress infection and speed recovery

Histamine

substance that increases the permeability of surrounding capillaries

Phagocytes

type of white blood cell that pass through capillary walls, ingest and destroy foreign matter

Neutrophil

type of phagocyte that squeeze through capillary walls

Macrophage

type of phagocyte that engulfs pathogens and cellular debris

Natural Killer Cells

large white blood cells that attack pathogen-infected cells

Complement System

proteins... Continue reading "Understanding Infectious Diseases and the Immune System" »

Fundamental Biological Processes

What is Germination?

Germination is the process of seeds developing into new plants.

What is Growth?

An increase in the size of an organism or part of an organism, usually as a result of an increase in the number of cells.

What is Respiration?

The transfer of oxygen from the outside environment to cells within tissues, as well as the removal of carbon dioxide in the opposite way.

What is Photosynthesis?

The process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen.

What is Interdependence?

Organisms depend on each other for survival. This is called interdependence.... Continue reading "Fundamental Biological Processes and Cell Structure" »

Plant Nutrition

Photosynthesis: The process by which plants manufacture carbohydrates from raw materials using energy from light.

Key Aspects of Photosynthesis and Respiration

• Chlorophyll: Transfers light energy into chemical energy stored in molecules, essential for the synthesis of carbohydrates.
• Carbohydrate Use and Storage: Aside from using complex carbohydrates to create the plant's structure, plants store carbohydrates or use them for energy to grow.
• Respiration: To utilize stored carbohydrates, plants take the glucose formed during photosynthesis and combine the carbohydrate with oxygen—a process called respiration—to release energy.
• Role of Chlorophyll and CO₂: Chlorophyll is required because it helps absorb the light needed for photosynthesis.

Respiratory System Components

• 1 Nose
• 2 Mouth
• 3 Larynx
• 4 Right lung
• 5 Right bronchus
• 6 Diaphragm
• 7 Pharynx
• 8 Trachea
• 9 Left bronchus
• 10 Bronchiole
• 11 Alveoli

Characteristics of Alveoli for Gas Exchange

The epithelium of the alveoli is monostratified, consisting of a single layer of extremely flattened epithelial cells. Similarly, the capillary epithelium consists of a single layer of flat cells, known as the endothelium. The alveoli are covered by a vast network of capillaries to facilitate efficient gas exchange.

How Air Is Cleaned, Moistened, and Warmed

The nose filters inhaled air using hairs that trap particles. Additionally, as air passes through the nasal cavity, it is warmed and moistened.

Understanding the Endothelium

The endothelium forms the thin walls... Continue reading "Human Respiratory and Digestive Systems: Key Functions" »

Understanding Inheritance and Continuous Variation

This type of inheritance refers to continuous characteristics regulated by genes that are inherited independently.

Sometimes, continuous variation does not only depend on one quantitative inheritance but also on the influence environmental factors have on the genotype. The height and weight of a population are classic examples of continuous characteristics that are affected by environmental factors.

Mendel's Laws of Inheritance

Mendel's First Law: Law of Uniformity

When two pure-bred individuals are crossed, all offspring of the first filial generation (F1) have the same genotype and phenotype.

Mendel's Second Law: Law of Segregation

When two individuals from the first filial generation are crossed,... Continue reading "Understanding Inheritance, Cell Theory, and the Origin of Life" »

Accessory Digestive Organs

• Salivary Glands: Parotid, sublingual, and submandibular.
• Tongue/Teeth
• Liver: Produces bile (a fat emulsifier), stores vitamins A, E, D, and K, and aids in detoxification.
• Gallbladder: Stores and concentrates bile.
• Pancreas: Located posterior to/under the stomach. Produces insulin (for transport of sugar into cells) and pancreatic juices capable of breaking down proteins (protease), carbohydrates (amylase), and lipids (lipase). These enzymes pass into the duodenum (small intestine) through the pancreatic duct.

Terms

• Digestion: Process of changing food to a state where it can be used by the body.
• Metabolism: Includes all of the processes involved in the body's use of nutrients.
• Catabolism: Breaking down of body cells or substances,

Ovaries:

• Composed of ovarian follicles (sac-like structures)

Gametes

produced by gonads

Uterus:

• Located between the urinary bladder and rectum
• 3 layers: 1. Endometrium 2. Myometrium 3. Perimetrium
• Functions of the uterus:
  • Receives / retains a fertilized egg
  • Nourishes the fertilized egg

Penis:

• Delivers sperm into the female reproductive tract
• Regions:
  • Shaft
  • Glans penis (enlarged tip)
  • Prepuce (foreskin)
• Internally 3 areas of spongy erectile tissue around the urethra

Ovulation:

when the egg is mature the follicle ruptures

Haploid:

1N

Oocyte:

The oocyte is viable for 12 to 24 hours after ovulation

Sperm:

are viable for 12 to 48 hours after ejaculation

• Sperm cells must make their way to the uterine tube for fertilization to be possible

Fertilization:

When sperm nucleus... Continue reading "Female Reproductive System and Endocrine Glands" »