The second year of biology experiment to raise silkworms
The following is an example of raising silkworms in the second year of biology: ** 1. Purpose of the experiment ** By raising silkworms and observing the growth and development process of silkworms, they could understand the characteristics of complete metamorphosis. ** 2. Experiment Equipment ** Scissors, writing brush, silkworm rearing tools, silkworm eggs, mulberry leaves, magnifying glass, paper box, cotton paper, etc. ** 3. Experimental Steps ** 1. ** Silkworm egg hatching stage ** - ** Prepare the incubation environment **: - A layer of tissue paper was laid at the bottom of the paper box, and some small holes were pricked on the lid to ensure air circulation. Put the silkworm eggs in a paper box and place them in an environment with a temperature of about 26 ° C and a humidity difference of 3 - 4 ° C (it can be adjusted according to the actual situation. Generally, it is more suitable in the warm season at the end of spring). The room can be shaded, and the next morning, light exposure can promote the hatching of small silkworms (ant silkworms). - Observing the changes of the silkworm eggs, the silkworm eggs were light yellow when they were just laid, flat oval, about 1.3 mm long. During the hatching process, the color of the silkworm eggs would gradually change from light yellow to yellowish-brown, and finally to purple-black. - ** Treatment of the newly hatched silkworm **: The newly hatched silkworm is black, thin, small, and has fine hair. 2. ** Silkworm Rearing Stage ** - ** 1st and 2nd instar silkworms **: - The first and second instar silkworms had to be fed with chopped, fresh, tender mulberry leaves. When changing mulberry leaves, you can use a brush or feather to move the silkworms. The temperature of the feeding environment was maintained at 26 - 26.5 ° C, with a difference of 3 - 4 ° C between humidity and humidity. - The characteristics of silkworm dormancy: Before silkworm dormancy, the amount of food consumed will be reduced, and excrement may be discharged. The color of the body will darken and look a little yellow, and there will be the phenomenon of not eating or moving, and the head will be raised high. After hibernation, the silkworm will shed its skin. When it shed its skin, the front half of its body will lie down, and the whole body will move in waves. Then, the new skin will be exposed, and the whole body will crawl forward to get rid of the old skin. Finally, the old head shell will fall off by shaking its head. - ** Silkworms of 3rd instar and later **: - After the third instar, the silkworm's body grew up and could be fed in a large box. The mulberry leaves did not have to be all young leaves. The mulberry leaves were given 3 - 5 times a day. - From the newly hatched silkworm to the fifth instar silkworm, it shed its skin four times. Every time it shed its skin, the silkworm would grow a little bigger. The third or fourth instar silkworms could be observed. Their bodies were about an inch long and grayish white. They were divided into three parts: the head, the chest, and the abdomen. The head was very small, with mouthparts for chewing mulberry leaves, a pair of antennae, and six single eyes on each side of the head. There were three pairs of chestlegs on the chest, a pair of stomachs on the sixth to eighth segments of the abdomen, a pair of tail legs on the tenth segment, and a tail horn on the back of the eighth segment. There were nine pairs of spiracles on the chest and abdomen for breathing. - ** Fifth Inch Silkworm **: At the fifth instar, the silkworm's body is oily and translucent, and it begins to spin silk. At this time, they can be placed on the straw handle to make cocoons. 3. ** Pupa Stage ** - The cocoon was taken ten days after spinning, and the cocoon shell was cut open to observe the pupa. The pupa was brown, spindle-shaped, divided into three parts: chest and abdomen. The head had antennae, the chest had three pairs of feet and a pair of wing buds, and the abdomen was divided into sections. 4. ** Adult (Silkworm Moth) Stage ** - Ten days later, the pupa turned into a moth and broke out. It can be observed that the female moth's abdomen is swollen, and the antennae are gray and comb-shaped; The male moth's abdomen is slender, and the antennae are black and feather-shaped. Both the female and male moths have wings. Silkworm moths lay eggs after mating and die after giving birth. ** 4. Observation and Record ** During the whole experiment, it was necessary to observe and record the time, shape, color, size and other characteristics of each growth stage of the silkworm, such as the color and shape changes of the silkworm eggs at different stages of hatching, the physical characteristics and behavior habits of the silkworm at different ages (such as sleeping, silking, etc.), the shape of the silkworm pupa, the appearance characteristics of the silkworm moth, and the difference between male and female. At the same time, the four stages of the silkworm could also be made into specimens for further observation. The methods of making specimens were as follows: dry storage of eggs, blowing-drying of larvae, soaking of pupas in 5% formalin, and air-drying of moths on wing-spreading plates (refer to more detailed specimen preparation materials). Read more exciting novels for free
National Talent Examination in the Second Half of 2020
In the second half of 2020, the International Talent English Test (referred to as the National Talent Test) was held in December in 89 cities in 30 provinces across the country at the same time. For example, the test was held in the Foreign Language School of Changchun Guanghua University and the Mass Creation Center of Zhengzhou University of Science and Technology. Tens of thousands of candidates from 1058 universities across the country participated. This exam included five categories: "Elementary","Intermediate","Advanced","Advanced", and "Advanced". The Foreign Language School of Changchun Guanghua University actively carried out work related to the National Talent Examination from the aspects of national talent propaganda, organization of registration, etc. Finally, 334 students applied for the examination. The online education center of the school's Academic Affairs Office and the Foreign Language School jointly organized the examination. The candidates actively prepared for the examination. Before the examination, they were familiar with the questions, the examination process, and the answer methods of the National Talent Examination to prepare for the smooth pass. Zhengzhou University of Science and Technology had made detailed arrangements for the layout of the examination hall, the guidance signs, the organization of the examination, the division of labor, the process of the examination, and other links. The school-enterprise cooperation office cooperated with the information center and the foreign language college to strictly follow the requirements of epidemic prevention and safety. They had achieved the goal of "measuring body temperature before entering the venue, wearing masks throughout the entire process, and disinfecting the entire venue after the end", and successfully completed the examination. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
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Here are some novels that involve scholars and landlords: The Landlord's Only Daughter has a plot between the scholar Ji Baorong and the landlord Xu Jialiang; The Prodigal Son of the Ming Dynasty has a story between the scholar and the landlord's silly son Fang Jifan; and there is a folk story called The Landlord Plays the Scholar. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
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Is it an idiom to be immortal
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What are the fourth grade primary school folk songs?
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Douluo Continent mods recommended lineup
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