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

Understanding Microorganisms and Disease

Viruses (e.g., flu, polio, common cold, AIDS, Ebola, chickenpox, measles, rubella, smallpox, mumps) are microscopic, measured in nanometers. Bacteria (e.g., tuberculosis, botulism, meningitis, tonsillitis, bronchitis, cystitis) are visible with an optical microscope, typically 1-5 micrometers. Fungi (e.g., athlete's foot, thrush, ringworm, candidiasis) are visible with an optical microscope, around 50 micrometers. Protozoa (e.g., malaria, dysentery) are also visible with an optical microscope, around 50 micrometers.

These microorganisms cause infectious diseases, which are illnesses that can spread to other people. Diseases not caused by pathogens are known as non-infectious diseases.

Vectors and Lifestyle

Digestive System Organs

Esophagus

• Tube approximately 25 cm long.
• Located behind the trachea and in front of the spinal cord.
• Drives the food bolus from the pharynx to the stomach.
• Its muscles produce peristaltic movements to ensure food reaches the stomach.
• Produces mucus, which favors food transit.

Pylorus

• A sphincter that communicates with the small intestine (duodenum).

Shared & Digestive System Components

Pharynx

• A duct located behind the mouth.
• Contains lumps called tonsils.
• Communicates the mouth with:
  • Esophagus
  • Back of the nostrils
  • Larynx
  • Middle ear

Epiglottis

• A flap located in the lower part of the pharynx.
• Closes the entrance to the larynx during swallowing.
• Prevents food from entering the respiratory tract.

Cardia (Cardiac Sphincter)

• A sphincter that

vitamin a : fish liver oils, animal liver. Function: required for normal immune system function and for production of cells in retina of eye. 

• Ecology is the scientific study of the interactions between organisms and the living and nonliving components of their environment.
• Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges.
• A population is a group of individuals of the same species living in an area.
• Population ecology focuses on factors affecting population size over time.
• A community is a group of populations of different species in an area.
• Community ecology examines the effect of interspecific interactions on community structure and organization.
• An ecosystem is the community of organisms in an area and the physical factors with which they interact.
• Ecosystem ecology emphasizes energy flow and chemical cycling

DNA Deoxyribonucleic Acid Forming Chromosomes

Stores genetic info DNA wounded to histones which becomes nucleosome loops onto chromatin

Codes for protein twisted into chromatid looped and packed into chromosome

Nucleotide Chromatin fibers are coiled and condensed to form chromosomes

consisting of a nitrogen-containing base Histones are proteins that help package and organize DNA in the nucleus of

(a, g, t, c.) or uracil in RNA eukaryotic cells by forming nucleosomes around which DNA is wrapped.

- phosphate group nucleosome is a basic unit of DNA packaging in eukaryotic cells

- sugar chromatid is one of the two identical copies of a replicated chromosome

Homologous Chromosomes chromosome is a long, coiled-up strand of DNA that contains genetic information

chromosomes... Continue reading "Understanding DNA, Chromosomes, and Genetic Variation" »

Trophic Levels

A trophic level consists of all organisms within an ecosystem that share the same feeding strategy.

Producers

Producers are autotrophic organisms that perform photosynthesis, using solar energy to convert inorganic matter into organic matter.

Consumers

Consumers are heterotrophic organisms that obtain energy by consuming other living organisms.

Primary Consumers

Primary consumers are herbivores that feed directly on producers.

Secondary Consumers

Secondary consumers are carnivores that feed on primary consumers.

Tertiary Consumers

Tertiary consumers (supercarnivores) are carnivores that feed on secondary consumers, such as lions.

Decomposers

Decomposers are heterotrophic organisms that break down dead organisms and waste products, returning... Continue reading "Ecosystem Dynamics: Trophic Levels, Food Chains, and Energy Flow" »

Allele Frequencies

Change in allele frequencies can be caused by:

• Natural selection
• Mutation
• Gene flow
• Genetic drift

Viral Reproduction

Steps of viral reproduction:

1. Attachment
2. Entry
3. Integration
4. Synthesis of viral components
5. Viral assembly
6. Release

Antibody Variable Regions

Primary function of the variable regions in antibodies: To bind specifically to antigens and determine the antibody's specificity.

Immunity

Innate Immunity

Innate (aka nonspecific) immunity is present at birth and functions the same way regardless of the pathogen. It involves:

• Phagocytosis
• Inflammation

In response to injury and/or pathogens, innate immune cells release paracrine signaling molecules such as cytokines and histamine that trigger inflammation. External pathogen features that can be... Continue reading "Biology Concepts Review" »

21)Signal Transduction is a process by which an extracellular signal molecule, called the first messenger activates a membrane receptor that in turn alters intracellular molecules, called the secondary messenger, to create a response.

Reproduction

We make new living beings similar to us. Men develop facial hair, deeper voices, more body hair, and bigger muscles. Women develop breasts, thicker lips, higher voices, and less body hair. The uterus is where the baby develops during pregnancy. Fallopian tubes connect the ovaries to the uterus. Ovaries contain the female sex cells, ova. The vagina connects the uterus to the outside of the body. The vulva is the external skin of the female reproductive system, which protects the opening of the vagina. The prostate gland produces a liquid that transports spermatozoa and provides them with nutrients, semen. The urethra is the tube that transports semen to the outside of the body. The penis is the organ that contains the urethra. Sperm... Continue reading "Human Reproduction: Anatomy and Process Explained" »