【题目】Paragraph 1: Pollen, a powdery substance,which is produce d by flowering plants an d con tains male reproductive cells, is usually carrie d from plant to plant by insects or birds, but some plants rely on the win d to carry their p ollen. Win d pollination is often seen as...
A.Pollen production requires a significant investment of energy and resources on the part of the plant. B.The capacity to produce pollen in large quantities is a recent development in the evolutionary history of plants. C.Plants in the tropics generally produce more pollen than those in temperate...
many individuals of the same species D-Wind-pollinated plants usually have small petalless flowers which often grow in catkins that produce a very fine-grained pollen E-Wind pollination requires production of a large am ount of pollen, which must be released at the right ti and under the ri...
根据空前“Bees, flies, animals and wind spread pollen(花粉)from one plant to another. To ensure the seeds will grow into plants, give them space.(蜜蜂、苍蝇、动物和风将花粉从一种植物传播到另一种植物上。为了确保种子能长成植物,应该给它们一定的空间)”可知,空前提出了花园里异花授粉的方式,有蜜蜂...
Most plants reproduce by making seeds,which sprout(发芽)and grow into new plants.To produceseeds,plants must be fertilized by pollen(花粉),usually from another plant of the same species.Manyplants rely on insects,such as bees and butterflies,to spread pollen.Seeds are mostly spread by animals...
C. Plants in the tropics generally produce more pollen than those in temperate zones. D. The highest levels of pollen production are found in plants that depend on insects or birds to carry their pollen. 你的答案: 正确答案:A 题目解析: ...
Power stations and industrial plants, which are often sited close to cities, can produce large quantities of the gas. As well as affecting human health, sulfur dioxide can be harmful to plants, turning leaves yellow and drying, bleaching, and even killing, foliage. In the atmosphere, sulfur ...
Windborne pollen is dry, rounded, smooth, and generally smaller than that of insect-pollinated plants. But size is a two-edged sword. [#highlight12]Small grains may be blown farther but they are also more prone to be whisked past the waiting stigma because smaller particles tend to stay ...
Therefore, they generate microspores, which will produce pollen grains as the male gametophytes, and megaspores, which will form an ovule that contains female gametophytes. Which of the following gymnosperms has branched stems? Solution: Answer: DSolution: Pinus and cedrus have branched stem. ...
allergies. The most common cause is pollen (花粉) which is usually produced by trees in the spring grasses in the summer and weeds in the fall as part of their reproductive process. Other causes include organisms chemicals plants and dead skin particles (微粒) from dogs and cats can also ...