Input: Answer this question:
Which two processes in the water cycle are primarily responsible for the creation of a lake?
OPTIONS:
- evaporation and runoff
- evaporation and condensation
- precipitation and runoff
- precipitation and condensation
Answer: precipitation and runoff

*Question*: A scientist is comparing two body cells of a multicellular organism. Which of the following is most likely identical? OPTIONS:
- shape of cell walls
- number of mitochondria
- shape of cell membranes
- number of chromosomes
*Answer*: number of chromosomes

question:
Which of the following is an example of a container that is filled with a pure substance rather than with a mixture?
OPTIONS:
- a tire filled with air
- a jar filled with salt water
- a balloon filled with helium
- a glass filled with chocolate milk

answer:
a balloon filled with helium

[Q]: Read the article below and answer the question. Spiders have been around for over 400 million years. Early spiders mainly used their silk to construct a hiding place. Today, although many spiders-such as giant tarantulas, trap-door spiders, and some other species-still use their silk mainly for shelter, most build various types of aerial webs. The primary victims of the spider's web are insects-a lot of insects. A British researcher once calculated that local farmland was home to more than two million spiders per acre, and that insects eaten annually by spiders nationwide would outweigh the human population. In fact, the change from ground-based webs to vertical, aerial webs was a reaction to the rise of winged insects. The increase in spiders in so many places is mainly because of their ability to move. To travel, a spider goes to a high point, lets out enough silk to catch the wind, and floats away. The spider may travel many miles this way. This helps them distance themselves from other spiders competing for food and also aids them in spinning a web across a gap they would otherwise have trouble crossing. Spiders release silk from silk glands called spigots to weave their webs. Hundreds of these spigots cover the three pairs of spinnerets that most spiders have. This allows spiders to combine multiple strands of silk into single threads with characteristics that differ for different uses. Some spiders, like tarantulas, only make one type of silk, but others make silk to use for drag lines, web frames, egg cases, or to trap insects. The webs also help spiders hide from predators such as birds. Other animals also make use of the spider's web. A Hymenoepimecis wasp will attack a Plesiometa argyra spider and sting it. While the spider is paralyzed, the wasp deposits her egg on the spider's abdomen. The spider goes about its business, catching and eating prey, while the wasp larva feeds on the spider's blood. Source: National Geographic, August 2001, pp. 32-44 The spider's ability to spin silk is
===
OPTIONS:
- an acquired trait.
- an inherited trait.
- a life cycle stage.
- a learned behavior.
****
[A]: an inherited trait.

question below:
Infectious diseases are caused by
OPTIONS:
- allergies
- vitamin deficiencies
- chemical spills
- microorganisms
answer below:
microorganisms

question below:
Waste Not: Energy from Garbage and Sewage A hundred years ago, gas was collected from rotting sewage and used to light street lamps. New technologies hope to update this concept-tapping garbage as well as human waste-for an energy-hungry world. One promising device is called a microbial fuel cell. It makes electricity much like a hydrogen fuel cell, but it runs off wastewater. Sewage-eating bacteria drive a chemical process that generates current and, as a bonus, helps purify the water. Bruce Logan of Pennsylvania State University and his colleagues have constructed small microbial fuel cells, no bigger than a can that can power various devices, including a small fan. "If you had 100,000 people and you treat their sewage, you could get up to 2.3 megawatts of continuous power, which is enough to supply electricity for 1,500 homes," Logan said. A megawatt is one million watts. A self-sufficient water-treatment device is also something that NASA is interested in. Bruce Rittman of Northwestern University is currently devising a microbial fuel cell that could be used on manned space missions. "You have to recycle everything up in space," Rittman said. "You want to capture food waste and human waste, as well as recycle water." A microbial fuel cell has some advantages over the more traditional method, called an anaerobic digester, which collects the methane, or "biogas," that bacteria belch out when they consume organic material in the absence of oxygen. The methane is later burned to turn a turbine generator. "Instead of going through the intermediate step of combustion, a cell makes the electricity directly," Rittman said. This direct route means that a microbial fuel cell could potentially extract more energy from a given amount of sewage. It also would avoid the pollution that burning methane produces. But both Rittman and Logan are quick to add that cells are still early in development, whereas digesters are in use, mostly in agriculture settings where the concentration of organic material is higher than from urban sewers. What type of energy do microbial fuel cells convert into electrical energy?
OPTIONS:
- kinetic energy
- nuclear energy
- chemical energy
- mechanical energy
answer below:
chemical energy