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Varvara68 [4.7K]
2 years ago
11

What does it mean to have parfocal objectives?

Biology
1 answer:
choli [55]2 years ago
5 0

There is a significant difference between parfocal objectives and objectives that are not. Having parfocal objectives means that the sample remains in focus when the objectives are changed.

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The most significant characteristic of parfocal objectives is that the image or sample under observation remains focused even when changing objectives.

When you are focussing a sample using a low-power objective and want to change to a higher one, you do not need to refocus anymore. And if you do, the adjustment is minimal. The focus keeps being the same because the distance between the image and the lens remains the same.

This characteristic turns to be convenient because

  • <em>it avoids spending time focusing, </em>
  • <em>it prevents contact between the lens and the coverslip. </em>

---------------------------------------------

Related link: brainly.com/question/2475359?referrer=searchResults

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Why do you think the ecological footprint of bangladesh is so small why is it so large for people in the united states?
EleoNora [17]

The ecological footprint of the average people of Bangladesh  is 0.5 global hectares per person which much less than  average of the world ( 2.84 global hectares per capita ) .it indicates that a low purchasing power of Bangladesh . less consumption means less production .also there are few industries in Bangladesh. This is the reason the ecological footprint of Bangladesh is so small .

The United states ecological footprint is larger than that of other countries because per capita consumption of energy and a wide range of goods of all kinds is greater . wastes ,including carbon dioxide ,are greater as ell , adding to the relative size of the footprint . this is the reason the ecological footprint of the people of United states is large .

Hence ,the ecological footprint of Bangladesh  is so small and the ecological footprint of United states is so large .

<h3>What is ecological footprint ?</h3>

The ecological footprint is a method promoted by the global footprint network to measure human demand on natural capital , i.e. the quantity of nature it takes  to support people or an economy .

It tracks this demand through an ecological accounting system .

The ecological footprint is the only metric that measures how much nature and how much nature we use .The footprint helps : countries to improve sustainability and well-being , local leaders to optimize public project investments , individuals to understand their impact on the planet.

Learn more about ecological footprint here:

brainly.com/question/14441911

#SPJ4

6 0
2 years ago
10 points
Tom [10]
Soil pH affects nutrients available for plant growth. In highly acidic soil, aluminum and manganese can become more available and more toxic to plant while calcium, phosphorus, and magnesium are less available to the plant. In highly alkaline soil, phosphorus and most micronutrients become less available.
The answer your looking for is true I believe
5 0
3 years ago
Umami taste receptors are capable of detecting _________ ______ in acidic foods and substances.
yarga [219]

Answer:

Amino acids and glutamates

Explanation:

Umami taste receptors or savory taste receptor is the fifth basic taste receptor derived its name from the Japanese name for the fifth basic taste  (which includes bitter, sweet, salty and sour tastes).

Umami is savory taste which includes the features of cooked meat as well as broth.

Umami taste receptors detects glutamates present in fermented food and meat broth. These receptors are also capable of detecting monosodium glutamate, GMP and IMP in meats, cheese, etc.

5 0
3 years ago
How do frogs utilize extensor and flexor muscles in order to swim, jump, and do other frog things efficiently; include specific
ahrayia [7]
<span>The structure of the feet and legs varies greatly among frog species, depending in part on whether they live primarily on the ground, in water, in trees or in burrows. Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them to do so. Most frogs are either proficient at jumping or are descended from ancestors that were, with much of the musculoskeletal morphology modified for this purpose. The tibia, fibula, and tarsals have been fused into a single, strong bone, as have the radius and ulna in the fore limbs (which must absorb the impact on landing). The metatarsals have become elongated to add to the leg length and allow the frog to push against the ground for a longer period on take-off. The illium has elongated and formed a mobile joint with the sacrum which, in specialist jumpers such as ranids and hylids, functions as an additional limb joint to further power the leaps. The tail vertebrae have fused into a urostyle which is retracted inside the pelvis. This enables the force to be transferred from the legs to the body during a leap </span>
<span>The muscular system has been similarly modified. The hind limbs of ancestral frogs presumably contained pairs of muscles which would act in opposition (one muscle to flex the knee, a different muscle to extend it), as is seen in most other limbed animals. However, in modern frogs, almost all muscles have been modified to contribute to the action of jumping, with only a few small muscles remaining to bring the limb back to the starting position and maintain posture. The muscles have also been greatly enlarged, with the main leg muscles accounting for over 17% of the total mass of the frog.</span>
7 0
3 years ago
3. The buccal cavity comprises ________,_______and __________.
Ostrovityanka [42]

The movement of food through the esophagus  is called peristalsis.

<h3>What is the buccal cavity?</h3>

The mouth is what we generally call the buccal cavity. It is an opening that contains the teeth and the tongue. The tongue plays the important role of serving as the organ of taste while the teeth serves to marsh food. It is the white strong structure that occurs in the mouth that enables is to masticate our food. Also in the mouth we have the salivary gland which plays the role of secreting the saliva and we know that the saliva contains from enzymes that makes it possible for the digestion of food to commence at the moth. It the follows that the buccal cavity is made up of the teeth, tongue and salivary glands.

Food moves into the stomach via the esophagus. Thus movement is slow and is aided by the muscles that line the gastro intestinal tract. As such, movement of food through the esophagus  is called peristalsis.

Learn more about peristalsis:brainly.com/question/15265456

#SPJ1

7 0
2 years ago
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