Search results for: 'single-celled organisms'

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By: HWC, Views: 2061

Euglenoids are single-celled organisms that live in lakes and ponds. A contractile vacuole pumps out the water that diffuses into the cell from its hypotonic surroundings. The body is covered by a translucent pellicle composed of flexible strips of a protein-rich material. Light passe...

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Global warming and its effect on climate change

By: HWC, Views: 7311

Global warming, habitat destruction, and pollution are all hot topics in the news. Environmentalists are concerned that many of these factors will lead to the loss of species. But how will this happen? One way to think about the environment is as a finely-tuned, high performance engine. If one...

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Fermentation - When Oxygen Is Absent, Pyruvate to Lactate & Pyruvate to Ethanol

By: HWC, Views: 7296

Pyruvate is the end product of glycolysis. If oxygen is present, pyruvate enters the mitochondrion where further energy yielding reactions of the Krebs cycle will take place. However, if oxygen is not present, pyruvate will enter a pathway called fermentation. This pathway regenerates NAD+ fro...

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Interspecific Competition Relationship - Competitive & Niche Differentiation

By: HWC, Views: 7423

In an environment with limited resources, any organisms that utilize the same resources will be in competition with each other. For example, let's look at two competing species of paramecium, a single-celled organism that feeds on bacteria. If we raise each of these species in isolation, both...

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

By: HWC, Views: 7622

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...

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Spermatogenesis Animation

By: Administrator, Views: 11092

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. T...

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Subunits of DNA And Semi Conservative Replication

By: HWC, Views: 4065

Adenine is a purine with a double-ring structure. In double-stranded DNA, adenine base-pairs with thymine. Guanine is a purine with a double-ring structure. In double-stranded DNA, guanine base-pairs with cytosine. Thymine is a pyrimidine with a single-ring structure. In double-stranded DNA, th...

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Generalized life cycles for plants and animals Animation

By: HWC, Views: 1790

But the life cycles of plants and animals differ in their details. In animals, a multicelled diploid stage gives rise to single-celled haploid gametes, the eggs and sperm. These gametes combine at fertilization to form a diploid zygote, which grows and develops into a new multicelled animal...

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Energy Flow - Trophic Levels and Food

By: HWC, Views: 7315

All of these relationships between different species are founded on one thing: energy. Organisms get food in order to get energy, which is used by the organism for growth, maintaining health, and reproduction. We can classify the members of a community according to how they obtain food. Produc...

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