rence Teixobactin is a new antibiotic discovered in 2015. It was the first antibiotic to be discovered for around 30 years. Extracts from soil bacteria had shown that the species Eleftheria terrae contained an antibiotic substance.This substance was effective against several pathogens of humans including Mycobacterium tuberculosis. However , this bacterium could not be grown in a lab and so a new technique had to be develope so that the bacterial cells could be grown in pure cultures (cultures that contain only one bacterial species) in the soil. The antibiotic purified from Eleftheria was called teixobactin. Teixobactin works by binding to a lipid molecule that some kinds of bacteria use to make their cell walls.The binding prevents the bacterium from using the lipids, so the cell wall is weakened Osmosis into the cell cause the bacterial cell membrane to burst Teixobactin is the first antibiotic to be developed that affects lipids.Other antibiotics usually act against proteins . Scientists hope that the way teixobactin works will reduce the risk of bacteria developing resistance to it, as they have to other antibiotics. Clinical trials of teixobactin are unlikely to happen before 2017 Those will take another two to three years, and the total cost of development, if the antibiotic is successful will be more than E50 million. It is uncertain ye whether any drug company will want to spend this amount to complete the testing, as they will not earn mone from the drug until it is used by doctors. 1 Explain what is meant by antibiotic. 2 Explain why Eleftheria terrae is difficult to grow in culture. 3 Explain the role of osmosis in the antibiotic effect of teixobactin. 4 Explain why teixobactin should be safe to use in human cells. 5 Pre-clinical testing of teixobactin has been done on infected human cells. Describe the remaining stage of testing that are needed before the new antibiotic can be licensed for use by doctors. Explain why each the stages is carried out. 6 The rapid rise in resistance of pathogenic bacteria to all antibiotics is of great concern. a Explain why this makes it essential that research finds new ways to control pathogenic bacteria. b Suggest how the risk of developing resistance to a new antibiotic explains the lack of development of new antibiotics. Extra challenge 7 There are millions of species of soil bacteria Suggest an explanation for why Eleftheria terrae makes teixobactin.

Orawing Conclusions About Brown Tree Ŝnakes The brown tree snake is native in areas such as Australia and eastern Indonesia. In those ecosystems, the brown tree snake is not causing the decline of bird or tree populations. So what makes this same species damaging in Guam? Identify some characteristics a species may possess that would fuel its ability to cause ecological damage, as the brown tree snake has in Guam. Provide some reasoning for why

A young researcher wants to test how well extremophiles, organisms that thrive in extreme conditions, live in different environments. She will do this by putting extremophiles of different species into different solvents. Because of limited lab space, she can run only one sample at a time, and each sample must remain undisturbed for 7 days. To reduce the total time needed to process all samples, the researcher decides to use two acidic solutions along with a control. The information below includes the extremophiles and the solvents the researcher will use in her tests. Species of Extremophiles T. prosperus A. aceti A. brierleyi H. acidophilum T. prosperus A. aceti A. brierleyi H. acidophilum Solvents Name pH hydrochloric acid 1.3 ascorbic acid 4.2 water 7.0 Name pH hydrochloric acid 1.3 ascorbic acid 4.2 water 7.0 Based on the tables, how many days will all of the researcher's experiments take? You may use the calculator. A. 7 B. 21 C. 49 D. 84

The terms in this sequence increase by the same amount each time. Work out the three missing terms to complete the sequence. 4rarr longrightarrow rarr longrightarrow longrightarrow rarr16 rarr

Which best describes oogenesis? Oogenesis involves mitosis but not meiosis. Oogenesis differentiates oogonia directly into eggs. Oogenesis starts in development and then halts until puberty Oogenesis happens in the testes

Question 24 of 25 What do prokaryotes and eukaryotes have in common? A. They both have chloroplasts. B. They both have cell membranes. C. They both have a Golgi apparatus. D. They both have a nuclear membrane.

What is 6% written as a decimal?

QUESTION 3 (a) State two (2) types of respiration. [ 2marks] (b) State the major differences between the two types of respiration mentioned in (a). [10 marks] (c) Describe the phases of Krebs cycle that produces carbon dioxide and ATP.

Clear my choice Peristalses Select one: a. The process of involuntary muscle contractions occurring in the esophagus that pushes food toward the stomach. b. The first section of the small intestine that connects in the liver and pancreas. c. Part of the urinary system, it is a reservoir for storing liquid waste in the form of urine. When urine levels are high, it sends signals to the brain that the liquid needs to be expelled. d. Small pear-shaped organ that stores excess bile produced by the liver. When the bile is needed it is released into the duodenum.

The diagram shows the unit that makes up DNA. What is it called? Enter your answer

GCE I 992 (Biology) Ouestion 3a State briefly, the symptoms shown by the deficiency of the following" Vitamin A Vitamin C Vitamink SSSCE 1994 (Practical paper) Q5. (b) State the functions of each of the food substance Foodsubstance function Fatsandoils Protein Vitamins Mineral salts Water Roughage To help food passes through the system move easily during digestion. It heips digestion to take place easily and prevent constipation. For the rest refer to notes. GCE 1993 Q3. (i) List three sources each of vitamin C and D (ii) For each vitamin, mention one disorder associated with its inadequate supply in the human body (Deficiency). Refer to notes. S.S.S.C. E. 1998 2. d. (i) Give two characteristics of the food substances: (a) protein (b) vitamin D (ii) State two uses of each of the food substances listed in (i) above to human. (iii) Describe briefly the role of roughage in the diet of humans. S.S.S.C.E. 1999 SECTION B 2 a (i) What is malnutrition? (ii) State three effects of malnutrition. S.S.S, C. E. 2002 Cancelled Que. 3d (i) Give three effects of malnutrition on humans (ii) Name two sources of vitamin A. S.S.S.C.E. 2003. What is photosynthesis? Explain how the roots of the plant obtain energy. What is a flower? State three importance of a flower. S.S.S. C.E. 1993 (practicals) 5 a (i) In testing for certain for substance in a sample, the following steps required: F-heating the test tube until contents boil II-Pour a little of the sample into a test tube III-Brick-red precipitate appears IV-Pour a little Benedict's solution into the test tube. Re-arrange and copy the above in the order in which they should occur. (ii) Which food substance could be tested for using the above steps? (iii) Which alternative reagent could be used in? b. A student placed a few drops of iodine solution on a piece of bread. (i) What observation is he likely to make? (ii) What conclusion could be draw from the observation in b (i)? (iii) The student chewed bread for about three minutes and transferred it on a watch glass. He then added a few drops of iodine solution. Describe briefly what he is likely to observe. What conclusion could be drawn from b (iii) above?