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Darwin's Observation (Fossils, Galapagos Islands & Africa ) and Natural Selection (Adaptive Traits)

By: HWC, Views: 6567

Along Darwin's voyage, he made many observations. Each one added to his understanding of how organisms change over time. Darwin was already familiar with fossils and knew that many fossils were very different from living organisms. But, also there were some fossils that were very similar to li...

Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 6096

`Natural selection' is the process in which organisms with adaptive traits survive and breed in greater number than organisms without such traits. Eventually, almost all of the individuals in the population will have the same adaptive trait. This was the concept presented by Charles Darwin in ...

DNA Replication Factory and Protein

By: HWC, Views: 6149

DNA (deoxyribose nucleic acid) carries all the genetic information needed to re-create itself and to pass on the characteristics of the organism. The “factory” model of DNA replication hypothesizes a specific nuclear structure in which the molecular machinery for replication forks are brou...

Photosynthesis and Van Helmont Experiment

By: HWC, Views: 5944

All energy on Earth comes from a star, the Sun. Light must travel 160 million kilometers to reach Earth where plants capture this light energy and convert it to chemical energy in the form of sugars. This biochemical process is called PHOTOSYNTHESIS. The summary equation for photosynthesis is ...

Chloroplast Structure & Light Dependent Reactions (Photosystem 1 and 2 Cyclic Electron Flow)

By: HWC, Views: 6302

The leaf is the principle photosynthetic organ of the plant. This is a cross section of a leaf. The rectangular-shaped cells are part of the photosynthetic tissue called the palisade mesophyll. Each photosynthetic cell can contain several hundred organelles known as chloroplasts. The chlorop...

Calvin cycle (The light-independent reactions )

By: HWC, Views: 6429

The light-independent reactions of photosynthesis occur in the stroma of the chloroplast. Carbon dioxide enters the leaf through tiny pores or stomata and diffuses into the chloroplast. The first stage of the Calvin cycle is the attachment of a carbon dioxide molecule to a 5-carbon ribulose bi...

How antibiotics works? 💊

By: HWC, Views: 6353

The Crisis in Antibiotic Resistance More than 70 years ago, Alexander Fleming discovered penicillin. A few decades later, when this antibiotic was used in World War II, Fleming's discovery had revolutionized medicine. No longer did people have to die from something as trivial as an infected cut.Y...

Mendel's Principles of Dominance, Segregation and Independent Assortment

By: HWC, Views: 6176

Mendel selected true-breeding parents with contrasting traits, for example, purple and white flower color, and performed reciprocal crosses by choosing pollen from one parent and hand pollinating the seed-forming parent with this pollen. A cross-fertilization resulted from this procedure. In t...

Molecules, Membrane Permeability and Structure

By: HWC, Views: 6168

Organisms are not isolated system at equilibrium and need to intake nutrients and electrolytes as remove wastes. Similarly Cells within an organism must also exchange compound by passing them through membrane. The permeability of a membrane is the rate of passive diffusion of molecules th...