Advanced Botany

  Insect repellents reduce malaria transmission by minimizing mosquito-human contacts. The most commercially available repellent formulations are either synthetic such as N,N-Diethyl-meta-toluamide-DEET or derived from plant extracts like Neem, Citronella, fennel or Pyrethrum grasses. N,N-Diethyl-meta-toluamide-DEET is the oldest and most effective insect repellent available on the market, but research have reported occasional mild-to-severe toxicity reactions following the application of DEET on the skin. Essential oils from plants represent suitable alternatives for repellent as they are less expensive and relatively safe. Recently, scientists have analyzed the mosquitoes repellent activity of essential oils from leaves of a plant namely  Tithonia diversifolia  against  Anopheles coluzzii  which is a major vector of malaria in Africa.  Anopheles coluzzii  is one of the main mosquito species responsible for malaria transmission in endemic countries....

  Like other living organisms, plants also respond to light, temperature, moisture, and sound.  It is claimed that sound and music has positive effects on plant growth and development. In addition, sound also alerts plants of potential danger and aids in defense and  facilitates   mutualistic interactions such as buzz pollination.  Studies report that exposure to specific biotic sounds elicits different physiomorphological changes in plants, suggesting that plants can perceive and respond to animal sound.  Arabidopsis  plants infested by caterpillar  Pieris rapae  defend themselves by producing higher levels of anthocyanin and glucosinolates. By contrast, however, exposure to other environmental sounds such as wind and leafhopper sound did not elicit such a response. Similarly,  Nicotiana tabacum  produces nicotine to deter herbivores .  Plants treated with the chewing sound of the caterpillar  Phtorimaea operculella ...

Lactose is the main source of sugar from milk and milk products from all mammals except the sea lion. Inadequate lactase activity allows lactose to reach the large intestine. There, the gut flora provides a salvage pathway for lactose digestion by cleaving lactose into short-chain fatty acids and gas, mainly hydrogen (H2), carbon dioxide (CO2), and methane (CH4). Non-digested lactose can cause osmotic diarrhoea; products of its bacterial digestion can lead to secretory diarrhoea and gas distending the intestines, events that are likely to lead to clinical symptoms.  Lactose malabsorption actually refers to inefficient digestion of lactose due to reduced expression or impaired activity of the enzyme lactase. After ingestion, lactose passes into the small intestine where it comes into contact with lactase at the intestinal brush border where it is hydrolysed into the monosaccharides glucose and galactose, which can be readily absorbed. Dis accharide digestion occurs on the brush bord...

  The word 'carbohydrate' was coined more than 100 years ago to describe a large group of compounds include polymers and other compounds synthesized from polyhydroxylated aldehydes and ketones. In general carbohydrates have the empirical formula (CH 2 O) n . They are polyhydroxylated aldehydes or ketones and their derivatives. Chemically, carbohydrates are molecules that are composed of carbon, along with hydrogen and oxygen. The compounds carbohydrates have common same functional groups, glyceraldehydes and gulose are classifed as aldoses and ribulose and dihydroxyacetone as ketoses. All of these compounds are alcohols with many hydroxyl groups. They are polyhydroxylated and either aldehydes or ketones. Classification of carbohydrates Monosaccharides The simplest and smallest unit of the carbohydrates is the monosaccharide, (mono = one, saccharide = sugar). Monosaccharides are either aldehydes or ketones, with one or more hydroxyl groups; the six-carbon monosaccharides g...

  Vitamin D is essential for maintaining healthy bones and teeth. It also has several other important functions in the body such as regulating the absorption of calcium and phosphorus and facilitating normal immune function. According to a study, vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] < 50 nmol/L or 20 ng/ml) is associated with fractures and bone loss. Severe vitamin D deficiency with a 25(OH)D concentration below <30 nmol/L (or 12 ng/ml) increases the risk of excess mortality, infections, and many other diseases. Poor vitamin D status is a global health problem. Approximately one billion people worldwide suffer from vitamin D insufficiency because most foods including plants contain little vitamin D. Sources of vitamin D Fish have the highest natural content of vitamin D (salmon contains 30 μg/100 g and tuna 2.9 μg/100 g). Other sources of vitamin D 3  are meat (~0.6 μg/100), egg (~1.75 μg/100) and milk products (~0.1 μg/100). Vitamin D 3  ha...

  Sun is the ultimate source of energy for the earth. Plants convert light energy from the sun into  chemical energy  (food) by the process of photosynthesis. All living beings depend on plants for food and oxygen. Animals would disappear from the Earth if photosynthesizing plants were to disappear, since animals require for their nutrition the complex organic compounds that can be synthesized only by plants. The animal excretions and the animal body after death are also converted by a process of decay to simple products that can be re-utilized only by plants. Green plants require carbon dioxide, water, mineral salts, and sunlight for the formation of carbohydrates. Not only carbohydrates, but plants also synthesize amino acids, proteins, lipids, pigments, and other organic components during photosynthesis. Instead of energy, plants also need chemical compounds to interact with their neighbors, to attract animals for pollination and to defend themselves from animals that ...