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In natural selection, negative selection [1] or purifying selection is the selective removal of alleles that are deleterious. This can result in stabilising selection through the purging of deleterious genetic polymorphisms that arise through random mutations.
This signaling network illustrates the simultaneous positive and negative feedback loops whose exquisite sensitivity helps create a bistable switch. Bistability can only arise in biological and chemical systems if three necessary conditions are fulfilled: positive feedback , a mechanism to filter out small stimuli and a mechanism to prevent ...
Stabilizing selection (not to be confused with negative or purifying selection [1] [2]) is a type of natural selection in which the population mean stabilizes on a particular non-extreme trait value. This is thought to be the most common mechanism of action for natural selection because most traits do not appear to change drastically over time. [3]
Unlike negative staining, positive staining uses basic dyes to color the specimen against a bright background. While chromophore is used for both negative and positive staining alike, the type of chromophore used in this technique is a positively charged ion instead of a negative one. The negatively charged cell wall of many microorganisms ...
A yellow on black or white-coloured background is used behind a black biohazard symbol when integrated with a CAUTION sign, label or paragraph. A green on white or white-coloured background is used behind a black biohazard symbol when integrated with a NOTICE sign, label or paragraph. DANGER is used to identify a biohazard that will cause death.
In biology, phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs. This causes the plant to have ...
Chemotropism seen in Yeast. Haploid Yeast cells release a- and α-factors that bind to the receptors of another haploid Yeast cell. The two Yeast cells fuse together to form an a/α diploid zygote. Fungal chemotropism was first reported over 100 years ago by Anton de Bary. [13] One example of fungi using chemotropism is seen in Yeast.
The implicit-association test (IAT) is an assessment intended to detect subconscious associations between mental representations of objects in memory. [1] Its best-known application is the assessment of implicit stereotypes held by test subjects, such as associations between particular racial categories and stereotypes about those groups. [2]