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Scientific FAQs | Dr. Caroline Leaf

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Distorted young leaves covered with can be a problem in the spring. These small sucking insects feed on the new growth as it begins to expand causing distorted leaf shapes. In large number, their sucking damage causes new leaves to twist and curl. A secondary problem is aphids excrete a sugar solution called "honeydew"…a perfect food source for the sooty mold fungus that grows on the honeydew causing plant leaves to look like they are covered in black soot. The fungus isn't actually parasitizing plant tissue, but it coats the leaves to such an extent that plants can't photosynthesize efficiently. In time, natural predators will help. The most famous is the ladybug, whose larval stages eat quantities of aphids. There are other predators, too. As a last resort, insecticides are available. The aphids can be controlled with Orthene, Malathion or Diazinon.

Science Experiments on Environmental Education and Biology

Black Vine Weevil, and Strawberry Root Weevil, Adult snout beetles are 3/8-inch long, black, with small yellow spots on the back. All adults are females capable of laying as many as 500 eggs. These eggs are laid in the soil. Adults are seldom seen because they feed on the foliage at night and hide in plant debris or in the soil during the day. The larvae are inch long, white and legless grubs. This pest over-winters as larvae in the soil; the adults emerge in early June. There is one generation per year. The adults feed at night by notching the leaves. This damage is seldom serious. The grubs or larvae can be highly destructive since they feed on the roots from mid-summer into late fall and again in the spring. In heavy infestations, most of the small feeder roots are destroyed; larger roots and crowns may be girdled. As a result, there is little or no plant growth, the foliage is often yellowed and may dry out. This pest is difficult to control since it is nocturnal and every adult is capable of reproduction. Larvacidal drenches may be used to kill them but are of limited effectiveness. Foliar sprays are very effective at controlling adult weevils when leaf notching starts. Foliar sprays must be repeated until no adults emerge. Orthene gives good control when applied as a foliar spray and drench. Foliar sprays must be repeated until no adults emerge. Orthene gives good control when applied as a foliar spray and drench. Since weevils can't fly and spend part of each day in the soil or mulch and part of each day feeding, you can paint the trunks with to stop them, but make sure no branches are touching the ground. Some people report that keeping the mulch layer away from the trunk reduces weevil damage if they make sure no branches are touching the ground. [Photos courtesy of Harold Greer] Also see

Banana Expert System - TNAU Agritech Portal

Texas A&M Forest Service - Trees of Texas - How Trees Grow

McCree (1972a) noted that the relative quantum yield for crop plant photosynthesis has two peaks at 440 nm and 620 nm. He also noted however, the , which states that photosynthesis in the presence of two or more wavelengths can be more efficient than the sum of that due to the individual wavelengths. In particular, adding white or red light (less than 680 nm) to deep red light (greater than 680 nm) can beneficially increase the rate of photosynthesis.

Green light is also used in photosynthesis, as can be seen from the leaf action spectrum (FIG. 2). It has been established that green light drives photosynthesis more effectively than red or blue light deep within the leaf (Terashima et al. 2009). Further, the insects used in greenhouses as pollinators and biological control agents see best in the green and ultraviolet regions of the spectrum. More interestingly, changes of even 10 nm in the peak wavelength of green light can have dramatic effects on the growth of plants such as lettuce (Johkan et al. 2012).

Identify the pest - Annette McFarlane

The buds, root tips, and cambium layer are the three growing parts of the tree

Sometimes leaf temperature is more important to plants then air temperature. Leaves function as solar collectors, that is, they are designed to absorb light energy. They do this in order to build sugars and produce other products necessary for life (and yield). However, very little of the light energy is actually used to do this work (photosynthesis). Light energy not used for photosynthesis causes leaf temperature to rise.

Nearly all of the chemical reactions necessary for the life of plants are controlled by enzymes (proteins). The rates of these chemical reactions increase with temperature, so, for example, plant growth and weight gain are greater at 80° than at 50°. These enzymes have a three-dimensional shape and can warp (change shape) at high temperatures. An extreme example of temperature affecting protein is the frying of an egg. The heat causes the egg protein to change its shape and become solid. The effect of temperature on plant enzymes isn't nearly that dramatic, but temperatures of 100 to 105 degrees can affect the shape of plant enzymes. When the shapes of the enzymes change, they no longer work as well. In other words, the reaction rate decreases. That is why 86° is often given as the optimum temperature for corn and soybean growth. Although the optimum is fairly flat for about 10 degrees, temperatures above the optimum slow many of the important reactions including those involved in photosynthesis.

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Dysbiosis - Bacterial, Fungal & Parasitic Overgrowth

Leaf colour along with shape and size of the leaves is ofimportance in varietal identification. The leaf of Rose Scented is boat-shapedwhile China has a distinctive twist along the length curved upward from themidrib and down along its length. Small leaflets of Bedana are oval shaped. Thefruit shape of the lychee is very distinguishing. The round shape of Bedana isdistinguished from the oblong shape of China or Shahi. The fruit is smooth andpulp is even or uneven. The apex of the fruit can be round, obtuse, blunt as inShahi, or pointed as in China. The varieties can also be distinguished dependingupon the colour of the new flush and season of flushing. Shahi produces verylight coloured flush while China has pinkish flush. Bedana has very dark pinkflush. Emergence of the panicle and its shape also differs. Singh and Singh(1954) distinguished the cultivars based on panicle characteristics. Shahi haslong panicles while Bedana produces short and compact panicles. The colour ofthe lychee fruit is pinkish brown or dark red depending on the cultivar. Colourof the skin varies and is also influenced by growing conditions.

Physiology of citrus fruiting - SciELO

It is also known as Early Seedless in Punjab because of itsearly ripening and small seeds. This cultivar has distinguishing leaf and flowercharacters. The cultivar is very much popular in Uttar Pradesh and Punjab. Treesare medium, attaining an average height of 5.0 m and spread of 6.2 m. It is amedium yielding cultivar (50-60 kg/tree) but bears fruits regularly. Fruits aremedium in size and weight ranges from 15 to 18 g having oval or heart shape,rough surface with uranium green skin covered with carmine red tubercles atmaturity. Aril is creamy white, soft, juicy and sweet containing 17.2 to19.80 brix TSS. Seed is very small, shrunken, glamorous, dirtychocolate in colour. The overall fruit quality of the cultivar isgood.

Fisiologia da frutificação em citrus

Stomatal closure may completely inhibit photosynthesiswithout eliminating water loss because the leaf cuticle of most trees is more permeable towater than to CO2 .

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