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

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" »

Understanding Aerobic Respiration

Aerobic respiration is a biological process that extracts energy from glucose and other organic compounds to create adenosine triphosphate (ATP) using oxygen.

The Four Stages of Aerobic Respiration

1. Glycolysis

   • Occurs in the cytoplasm.
   • A six-carbon glucose molecule is converted into two, three-carbon molecules of pyruvate.
   • This process occurs in the cytoplasm.
   • To initiate the process, two molecules of ATP are consumed. Four molecules of ATP and two molecules of NADH are produced.

2. Formation of Acetyl Coenzyme A

   • Involves shuttling pyruvate molecules into the mitochondrion.
   • Each pyruvate molecule is oxidized to carbon dioxide and a two-carbon acetyl group.
   • The carbon dioxide is released as a waste product, and the two-carbon

1. What are plant hormones?

Answer

Plant hormones are fluids secreted within the plant, also known as phytohormones. They regulate the growth and development of the plant. Examples of plant hormones are auxin and gibberellins.

2. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Answer

The movements of the leaves of the sensitive plant are touch-sensitive and independent of growth, while the movement of the shoot towards light is growth-related and known as phototropism.

3. Give an example of a plant hormone that promotes growth.

► Auxin

4. How do auxins promote the growth of a tendril around a support?

Answer

When tendrils come in contact with any support, the part of the tendril in contact... Continue reading "Plant Hormones and Reflex Actions: Questions and Answers" »