A contact lens is a lens placed on the cornea of the eye.
Importance of buffers in contact lens products:
Buffers: They aim to keep the pH of the solutions at values between 6.6 and 7.8 in order to maintain the lens parameters and the effectiveness of the solutions. They are made by the combination of an acid and its sodium salt (phosphate and acetate for example). Borate and citrate buffers are used.
Importance of isotonicity in contact lens products:
The solution composed by isotonic saline solution.
Isotonia is expressed by osmolarity or cryoscopic lowering
- 0.236 to 0.446 mOsmoles / l (increases during the day)
- If the osmolarity of the mixture is different from that of the tears, it causes discomfort and irritation
• Increased tear secretion
• Increase the blink frequency
- If hypotonia, entry of water to the epithelial cells, if hypertonia: inverse
- Osmolarity restored 1 or 2 minutes after instillation
Hi! Can you please make your question clearer ?
Answer:
cerebellum
Explanation:
The cerebellum is a small part of the brain positioned at the back of the head, where it meets the spine, which acts as the body's movement and balance control centre.
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Answer:
Answer is option A.
Vestigial features are fully developed and functional in one group of organisms but reduced and function less in a similar group.
Explanation:
- Vestigial structures are anatomical features such as cells, tissues or organs in an organism that are previously functional and performed some important functions in the organism but no longer serve any functions in the current form of the organism and become useless as a result of a large evolutionary change. Examples include the coccyx or the tailbone in humans, the pelvic bone of a snake, wisdom teeth in humans, nipples in human males, the wings of flightless birds such as kiwi, ostrich, etc.
- Homologous features are the features that are similar in different organisms having similar embryonic origin and development and are inherited from a common ancestor that also had that feature. Also, they might have different functions. An example is the presence of four limbs in tetrapods such as crocodiles, birds, etc.
- Analogous features are the features that are superficially similar in different organisms but had separate evolutionary origins i.e., different in origin, but similar in function. An example includes the wings on a fly, a moth, and a bird where the wings were developed independently as adaptations to perform the common function of flying.
- Polygenic features are the traits or features that are controlled by multiple genes that are located on the same or different chromosomes and are also affected by the environment. These features do not follow Mendel’s pattern of inheritance and are represented as a range of continuous variation. Examples of polygenic traits or features include skin color, height, hair color, eye color, etc. For example, there is wide variation in the human skin color (from light to dark) and height (short or tall or somewhere in between).
- Sympatry describes a species or a population that inhabit the same geographic region at the same time. In sympatric speciation, new species are evolved from a surviving ancestral species while both the species inhabit the same place at the same time i.e., in a single population, reproductive isolation occurs without geographic isolation.
Answer:
<em>They differ from both parents and also from each other. This occurs through a number of mechanisms, including crossing-over, the independent assortment of chromosomes during anaphase I, and random fertilization. When homologous chromosomes form pairs during prophase I of meiosis I, crossing-over can occur.</em>
Explanation:
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