The word "symptoms" is closest in meaning to ___________.

Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator. To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times. Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.

The word "their" in line 12 refers to .......

Which of the following is NOT true about algae?

According to the passage, red algae is________.

All of the following are mentioned as places in which memories are stored EXCEPT the:

The word “elaborate” in paragraph 3 is closest in meaning to ...........

The passage suggests that the tsunami resulting from the Krakatoa volcano .....

The word “mechanisms” in paragraph 1 is most likely ________.

The phrase “casts off” is closest in meaning to ..........

According to the author, M.L. ............... 

The biological community changes again as one moves from the city to the suburbs. Around all cities is a biome called the "suburban forest". The trees of this forest are species that are favored by man, and most of them have been deliberately planted. Mammals such as rabbits, skunks, and opossums have moved in from the surrounding countryside. Raccoons have become experts at opening garbage cans, and in some places even deer wander suburban thoroughfares. Several species of squirrel get along nicely in suburbia, but usually only one species is predominant in any given suburb -fox squirrels in one place, red squirrels in another, gray squirrels in a third - for reasons that are little understood. The diversity of birds in the suburbs is great, and in the South, lizards thrive in gardens and even houses. Of course, insects are always present. There is an odd biological sameness in these suburban communities. True, the palms of Los Angeles are missing from the suburbs of Boston, and there are species of insects in Miami not found in Seattle. But over wide stretches of the United States, ecological conditions in suburban biomes vary much less than do those of natural biome. And unlike the natural biomes, the urban and suburban communities exist in spite of, not because of, the climate

The word "thrive" is closest in meaning to ........