Trợ giúp bài tập về nhà môn Sinh học

which There are a lot of different kinds of __ live in water.some plants under the water. some live with part of the plant in the __ of the are often long and thin,.... not .... One plant,for example,has round leaves that live __ leaves are very big the water. __ ...................................................................... a car.They are stror are bigger __ ...................................................................... and children can ..... __ on them. Water plants look beautiful in and by lakes and rivers.

Câu hỏi What was significant about Fleming's work with penicillin? Select one: A. He was the first to use it to cure infections. B. He created a synthetic form of penicillin. C. He used it to treat diseases during World War I. D. He discovered penicillin could kill bacteria.

ANTIBIOTICS Antibiotics are substances that work in one of two ways Some antibiotics, such as penicillin, kill Others, such as tetracycline, stop them from multiplying. In 1675, Dutch scientist Antonie Van Leeuwenhoek, using a microscope, discovered microorgani known that they could cause disease until French scientist Louis Pasteur confirmed that approxi Finally, in 1928, British scientist Alexander Fleming noticed that a mold, penicillium growing in was capable of killing bacteria, and the development of antibiotics'became possible. Fleming nar the motd "penicillin" but was unable to create a drug from it. In 1940, during the Second World War two scientists working at Oxford University. Ernst Chain a able to make an antibacterial powder from penicillin that was safe to use on humans.Penicillin w use on soldiers in the war. If there had been no penicillin many would have died from bacterial inf injuries and wounds. Soon penicillin was used for serious diseases such as pneumonia and tuberci caused many deaths Fleming, Florey, and Chain received the Nobel Prize in 1945. Antibiotics char continue today to enable people to survive conditions that would have killed them before the antib Since their discovery and widespread use, antibiotics have been considered a wonder drug. Many c however, are caused by viruses, not bacteria, and antibiotics are not effective against them. Nevertl people use antibiotics regularly, believing they will cure viral illnesses such as common upper respi and sore throats. Why is this a problem?

A Beavers vary their dwellings according to local conditions.The inner chamber of their mound dwelling is positioned according to the level of the river in which it is situated. Once the mound is built the water rises up to meet the lodge or dwelling. During construction they dig an upward sloping tunnel into the riverbank which ends in a larger chamber underground about three feet across and two feet high. There is also usually a feeding chamber located near the entrance . Feeding generally occurs at night inside this chamber or outside on the river's edge and all food thrown away from feeding is disposed of directly into the water. Download to read ad-free B Another strategy is to attach the structure to existing trees or large rocks and further support these by heavy stones brought to the site. Gaps in the wall of the dam are filled with smal I branches leaves and other small materials and covered with mud or clay to make the dam completely water tight. The walls of the underwater entrance are smooth and steep. In front of the entrance is a clever deep pit where materials are gathered The pit also acts as a water current prote ction by reducing the speed and force of the water, protecting the structure. and repair the damage. Their mounds can reach a height of six to ten feet with hollowed-out living chambers inside,and entrances below water level.The largest recorded dam is in the Voronesh region of the former Sovie Union and measured about 3.800 feet long. 3 feet high and wide. In the swamps of the Mississippi basin and the Jefferson River in Montana beavers build dams over a thousand feet long which are strong enough to carry a person on horseback! C When the surrounding water level rises. threatening its home,beaver s have several options.They can go to the source of the problem - the water-and lower the top of the dam where the water runs over, thus lowering the water level. If this is not enough, they can remove chewed materials from the ceiling of the structure to build up the floor.Similarly, soil and small branches can be used to create a thicker and higher floor level. If the water level continues to rise, more twigs and mud can be added to the origina I structure. The main chamber can also be dug out further up. keeping the same angle of entry. In some areas, as in shallow,slow moving ponds,the beaver creates an island of and mud.If a hole develops in the dam they immediately find D Few species have the ability to manipulate the environment to their own ends as the beaver does. The dam.lodge, winter food store canals and runways are all part of a completely designed environme nt. The beaver and its dam, which at first might seem to be destructive rather than constructive.have wide effects on the ecology of the surrounding countryside. The dam raises the water table and slows drainage at the base of the dam by maintaining a steady flow of water in headstream s. The dam also prevents so I from washin downstream . And the rich soil that builds up soon supports a variety of plants that will attract other animals . Similarly, the systems of dams and pools provide food and habitat to other creatures, which in turn attract predators and the whole web of life is enriched. Questions 11-13 : Short-ans wer questions Answer the questions below . Choose NO MORE THAN TWO WORDS AN ID/OR A NUMBER from the text for each answer. 11 What is the maximum height that mounds can reach? __ 12 Which structure made by the beaver brings benefits to the local countryside? __ 13 What do the dams and pools provide for other animals? __

67. Những hạt bụi nào vào phổi nhiều nhất và gây hại nhiều hơn: A. bụi dưới 5 um B. Hạt bụi thô C. Bụi trên 10ụm D. Cả a và b đều đúng. 68. Bụi gây nhiều tác hại cho con người thường là các bệnh nào sau đây: a. Bệnh về đường hô hấp. b. Bệnh ngoài dA C. Bệnh trên đường tiêu hóa v.v... d Tất cả các bệnh trên. 69. Các biện pháp phòng chống bụi hiệu quả là: a. Thay đổi công nghệ sản xuất b . Thay đổi nguyên vật liệu C. Tổ chức hút và xử lý bụi d. Tất cả đều đúng. 70. Thiết bị lọc bụi nào dưới đây sử dụng nguyên lý trọng lực để lắng bụi: A. Thiết bị lọc bụi quán tính tĩnh điện B. Lọc bụi C. Lọc bụi tay áo D. Lọc bui bằng lưới lọc 71. Thiết bị lọc bụi làm cho hạt bụi bị mất động nǎng và rơi xuống dưới đáy là; a. Thiết bị lọc bụi kiểu quán tính.b. Thiết bị lọc bụi tĩnh điện. C. Thiết bị lọc bụi kiểu ly tâm. d. Buồng lắng bụi. 72. Mục đích của thông gió là: a. Thông gió chống nóng. b. Thông gió chống bụi và hơi khí độC. C. Thông gió chống nóng và khử độC.. d. Cả a,b đều đúng. 73. Mục đích của việc đảm bảo ánh sáng trong lao động là: a.Phân biệt được các chi tiết cần thao táC. Giữ được khả nǎng làm việc lâu hơn và không bị mệt mỏi. C.Cả a,b đều đúng. d.Cả a,b đều sai.