Traditionally, pollination (授粉) by wind has been viewed as a reproductive process marked by random events in which the vagaries of the wind are compensated for by the generation of vast quantities of pollen, so that the ultimate production of new seeds is assured at the expense of producing much more pollen than is actually used. Because the potential hazards pollen grains are subject to as they are transported over long distances are enormous, wind-pollinated plants have, in the view above, compensated for the ensuing loss of pollen through happenstance by virtue of producing an amount of pollen that is one to three orders of magnitude greater than the amount produced by species pollinated by insects.
However, a number of features that are characteristic of wind-pollinated plants reduce pollen waste. For example, many wind-pollinated species fail to release pollen when wind speeds are low or when humid conditions prevail. Recent studies suggest another way in which species compensate for the inefficiency of wind pollination. These studies suggest that species frequently take advantage of the physics of pollen motion by generating specific aerodynamic environments within the immediate vicinity of their female reproductive organs. It is the morphology of these organs that dictates the pattern of airflow disturbances through which pollen must travel. The speed and direction of the airflow disturbances can combine with the physical properties of a species’ pollen to produce a species-specific pattern of pollen collision on the surfaces of female reproductive organs. Provided that these surfaces are strategically located, the consequences of this combination can significantly increase the pollen-capture efficiency of a female reproductive organ.
A critical question that remains to be answered is whether the morphological attributes of the female reproductive organs of wind-pollinated species are evolutionary adaptations to wind pollination or are merely fortuitous. A complete resolution of the question is as yet impossible since adaptation must be evaluated for each species within its own unique functional context. However, it must be said that, while evidence of such evolutionary adaptations does exist in some species, one must be careful about attributing morphology to adaptation. For example, the spiral arrangement of scale-bract complexes on ovule-bearing pine cones, where the female reproductive organs of conifers are located, is important to the production of airflow patterns that spiral over the cone's surfaces, thereby passing airborne pollen from one scale to the next. However, these patterns cannot be viewed as an adaptation to wind pollination because the spiral arrangement occurs in a number of non-wind-pollinated plant lineages and is regarded as a characteristic of vascular plants, of which conifers are only one kind, as a whole. Therefore, the spiral arrangement is not likely to be the result of a direct adaptation to wind pollination.
62. The author of the passage is primarily concerned with discussing ______.
63. According to the passage, the “aerodynamic environments” mentioned in paragraph 2, when they are produced, are primarily determined by the ______.
64. The passage suggests that the recent studies cited in paragraph 2 have not done which of the following?
65. It can be inferred from the passage that the claim that the spiral arrangement of scale-bract complexes on an ovule-bearing pine cone is an adaptation to wind pollination would be more convincing if which of the following were true?
问题1选项
A.the current debate on whether the morphological attributes of wind-pollinated plants are evolutionary adaptations
B.the kinds of airflow patterns that permit wind- pollinated plants to capture pollen most efficiently
C.the ways in which the reproductive processes of wind-pollinated plants are controlled by random events
D.a recently proposed explanation of a way in which wind-pollinated plants reduce pollen waste
问题2选项
A.presence of insects near the plant
B.physical properties of the plant’s pollen
C.shape of the plant’s female reproductive organs
D.amount of pollen generated by the plant
问题3选项
A.Made any distinctions between different species of wind-pollinated plants.
B.Demonstrated that the morphological attributes of the female reproductive organs of wind-pollinated plants are usually evolutionary adaptations to wind pollination.
C.Indicated the general range within which plant-generated airflow disturbances are apt to occur.
D.Included investigations of the physics of pollen motion and its relationship to the efficient capture of pollen by the female reproductive organs of wind-pollinated plants.
问题4选项
A.Such an arrangement occurred only in wind-pollinated plants.
B.Such an arrangement occurred in vascular plants as a whole.
C.Such an arrangement could be shown to be beneficial to pollen release.
D.The number of bracts could be shown to have increased over time.
62.【试题答案】D
【试题解析】中心主旨题。题干意思是“这篇文章的作者主要是讨论……”。文章首先提出风媒传粉这一个繁殖过程,随后提出风媒传粉植物的一些特征减少了花粉的浪费并对其特征做出了论述,第三段则举例证明风媒传粉物种的雌性生殖器官的形态属性是对风媒传粉的进化适应这个问题还没有解决。通读全文可知,作者在文章中主要讨论的还是最近提出的关于风媒传粉能够减少花粉浪费这一解释,所以D项“一种最近提出的关于风媒传粉植物减少花粉浪费的解释”正确。A项“目前关于风媒传粉植物的形态属性是否是进化适应的争论”、B项“气流模式的种类允许风媒植物捕获花粉最有效”和C项“风媒传粉植物的繁殖过程受随机事件控制的方式”都只是文中提及的一部分。因此,该题选择D项正确。
63.【试题答案】C
【试题解析】细节事实题。题干意思是“根据文章,当第2段提到的‘空气动力环境’被生产时,它们主要是由______决定的”。根据题干关键词可以定位到第二段第三句These studies suggest that species frequently take advantage of the physics of pollen motion by generating specific aerodynamic environments within the immediate vicinity of their female reproductive organs.(这些研究表明,物种经常利用花粉运动的物理特性,在其雌性生殖器官附近产生特定的空气动力环境),结合第四句It is the morphology of these organs that dictates the pattern of airflow disturbances through which pollen must travel.(正是这些器官的形态决定了花粉必须通过的气流扰动的模式)可知,当空气动力环境产生时,雌性生殖器官的形态决定了这些气流的模式,所以C项“植物雌性生殖器官的形状”正确。A项“植物附近有昆虫”和D项“植物产生的花粉量”没提到,B项“植物花粉的物理特性”是空气动力环境的产生因素而并不是决定因素。因此,该题选择C项正确。
64.【试题答案】B
【试题解析】推理判断题。题干意思是“这篇文章暗示了第二段中引用的最近的研究没有完成以下哪一项?”。文章第二段描述了最近的研究得到的结果,而第三段对这个研究提出了问题,第一句指出A critical question that remains to be answered is whether the morphological attributes of the female reproductive organs of wind-pollinated species are evolutionary adaptations to wind pollination or are merely fortuitous.(一个有待回答的关键问题是,风媒传粉物种的雌性生殖器官的形态属性是对风媒传粉的进化适应还是仅仅是偶然的。),由此可以推断,第二段中引用的最近的研究并没有对风媒传粉植物雌性生殖器官的形态属性是对风媒传粉的进化适应提供有力的证明,所以B项“证明风媒传粉植物雌性生殖器官的形态属性通常是对风媒传粉的进化适应”符合题意。A项“对不同种类的风媒传粉植物进行了区分”、C项“表示植物产生的气流扰动易于发生的一般范围”和D项“包括对花粉运动的物理性质及其与风媒传粉植物雌性生殖器官有效捕捉花粉的关系的调查”都不是这个研究存在的问题。因此,该题选择B项正确。
65.【试题答案】A
【试题解析】推理判断题。题干意思是“从文章中可以推断出,如果下列哪一个是正确的,那么关于含有胚珠的松球的鳞苞综合体的螺旋状排列是对风授粉的适应的这种主张将更有说服力?”。根据文章倒数第二句However, these patterns cannot be viewed as an adaptation to wind pollination because the spiral arrangement occurs in a number of non-wind-pollinated plant lineages and is regarded as a characteristic of vascular plants, of which conifers are only one kind, as a whole.(然而,这些模式不能被看作是对风媒传粉的适应,因为螺旋排列发生在许多非风媒传粉的植物谱系中,并被认为是维管植物的特征,而针叶树只是维管植物的一种。)可知,含有胚珠的松球的鳞苞综合体的螺旋状排列不能被看作是对风媒传粉的适应是因为螺旋排列发生在许多非风媒传粉的植物谱系中,那么可以反推,如果螺旋排列只发生在风媒传粉的植物中,这些模式就能被看作是对风媒传粉的适应,故A项“这种排列只发生在风媒传粉的植物中”正确。B项“这种排列在维管植物中作为一个整体出现”错误,维管植物是非风媒传粉的植物。C项“这样的排列可以被证明是有利于花粉释放”和D项“苞片的数量会随着时间的推移而增加”不符合题干,且在文中不能推断出来。因此,该题选择A项正确。