Some farm land was flooded by storm water. Pollution from the flood made the soil much more acidic than it had been for hundreds of years. This made life more difficult for species living in the soil.

Which sentence do you think best describes what will happen?

A. Some species will disappear from the soil because they do not have individuals with traits that allow them to survive in more acidic soil.

B. Only some species will generate mutations needed to adapt to the change; other species will become extinct.

C. Most species will gain additional, genetically-based traits, that will allow them to live in the more acidic soil.

D. Only some individuals in each species will evolve the traits necessary to survive under these new conditions.

A ship that had been used for many years in cold Arctic waters was permanently moved to the warm waters of Sydney Harbour. Worms that had lived on the bottom of the ship crawled off into the warm water and attempted to attach to other ships in the area where there were no similar worms.

Some of the worms were able to survive and reproduce.

What do you expect will happen to this group of worms over many generations in this new, warmer environment?

A. The worms will mate and produce offspring just as they did in their previous environment, and the group’s traits will likely remain unchanged after many generations.

B. The worms will gain new, more complex traits through natural selection that will help them better adapt to the warmer waters because natural selection leads to more complex and better adapted organisms.

C. Worms possessing genetic variations that help them to survive and thrive in the new environment will leave more offspring than others lacking those traits. Over time, the proportion of the worm population with these adaptive traits will likely increase.

D. The mutation rate will increase in this group of worms in order to promote evolution.

A scientist studying a species of Wombats found that they live and burrow in areas that have three different types of soil:
 1. Mostly hard packed soil - Animals in the area with hard packed soil have thick, short claws.
 2. Mostly softly packed soil -  Animals in the area with soft packed soil have longer, thin claws.
 3. A mix of both hard & softly packed soil types -  Animals in areas where both types of soil exist have wide variations in claw shape.

Which statement best explains the areas where these animal types live?

A. In the past, all the animals moved from the mixed soil area into other areas. By chance, animals with thicker claws stayed in the hard packed soil areas and those with thinner longer claws stayed in the areas with less more loosely packed soil.

B. In the past, wombats with both claw types moved to both areas, but over time each individual changed its traits to the ones needed to live best in it's own chosen area: All the wombats in the hard packed soil had only the traits needed to live there and, similarly, the gophers living in the loosely packed soil areas changed their traits to suit the softer soil.

C. Animals with thick short claws can burrow more easily in hard soil, so in hard packed soil areas those animals with thicker claws were better able to survive and reproduce. In areas with loose soil, animals that thin long claws better for moving larger amounts of soil were the ones most likely to survive and produce offspring.

D. The animals in the hard packed soil areas needed to have claws adapted to hard soil, so a mutation arose to provide that trait. The animals in the less dense soil areas also needed to adapt, so they had a mutation that made their claws suitable for the soil type in their own area.

Scientists developed a new chemical spray to protected crops against insects.

The spray was widely used and, at first, was very effective. As time passes, insects are becoming more resistant to (less affected by) the spray. Why is this occurring?

A. Individual insects that have mutations that provide resistance so they can survive the spray. The survivors pass this resistance on to the next generation(s).

B. Resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of spray.

C. In the presence of the spray, individual insects evolve to become spray resistant.

D. Natural selection causes insects to generate genes providing resistance to the spray.

A cook sprayed a kitchen bench and surfaces with anti-bacterial cleaner. At the first, most of the bacteria was killed. However, even though he continued to spray, each week, the number of live bacteria increased.

Why did this happen?

A. Some bacteria had traits that allowed them to survive the spray. They produced offspring also carrying those traits.

B. After they are sprayed, the bacteria needed to adapt by developing spray-resistant traits.

C. The spray caused a mutation for resistance to it. This trait increased in the bacteria population over time.

D. The bacteria that tried hardest to become resistant to the spray left more offspring, who were also resistant.

A group of shoreline plants had existed for a long time under stable temperature and sea level. These plants were tall with very long roots and thin leaves (traits adapted for windy conditions well above the high tide line).

Due to global climate change, a  rise in sea level occurred and remained high over many plant generations.

Years later, scientists measured this same group of plants, and found that they became (on average) shorter, had much thicker leaves and had even longer roots - traits adapted for being submerged at each high tide.

Which theory is the most likely explanation for the change in the group:

A. The traits in the plant population changed randomly , and would have done so regardless of any increase in sea level.

B. Due to the increased sea level, mutations occurred that led to some of the plants being shorter with thicker leaves, allowing them to withstand being submerged at high tide.

C. Each plant evolved to become shorter with thicker leaves in order to thrive in this wetter environment. They then passed these traits on to their offspring.

D. Shorter plants with thicker leaves that already existed in the population were better able to thrive and generate offspring under the new conditions.

A group of plants is only pollinated by a particular bee. A disease wipes out all of the bees in the area where the plants live.

What is most likely to happen to this group of plants?

A.  A mutation will arise which will allow the plants to be pollinated by other insects.

B. Because they need to change their pollinators, some plant individuals will adapt to be pollinated by other insects.

C. This plant population will die off.

D. Enough variation exists within the plant population to allow it to adapt to any environmental change.

Male deer are growing smaller antlers than they did in the past because antler growth rate has decreased.

Some biologists suggest that this change is related to hunting because animals with larger antlers are most prized and therefore taken by hunters more often than animals with smaller antlers.

Which statement best explains the decreased antler size?

A The male animals know that if they grow big antlers, they will be hunted before they can reproduce, so they grow their antlers slowly and reproduce as quickly as they can.

B. Because male animals with large antlers are taken most often, more mutations occur to help the deer population reproduce before growing large antlers.

C. Male animals that reproduce with smaller antlers are likely to have more chances to reproduce because they are not as likely to be taken by hunters. They then pass on their slower antler growth rate to their offspring.

D. All animals in the group reduce their antler growth rate so that the entire population has smaller antlers.

Individuals in a large insect group have lots of different shaped mouthparts that they use to gather nectar.

Over time, a new food with flowers of different shapes, replaced the old one. Insects with shorter, thicker mouthparts were able to gather nectar more easily from the new type of flower.

Over multiple generations, what will likely happen to the variation of mouth parts within this insect group?

A. The variation in mouth parts will remain exactly the same because variation occurs randomly.

B.  Shorter, thicker mouth parts will become more prevalent in the insect population, although some variation will continue to exist.

C. The change in food source will lead to the occurrence of more mutations that result in shorter, thicker mouth parts.

D. Because natural selection favours shorter, thicker mouth parts, all individuals will have short, thick mouth parts after multiple generations.

Some adaptive traits, such as thicker fur or flowers of different colours, evolve over time within a group of organisms?

Which theory best explains why these changes occur?

A. Organisms with the current traits survived longer and had more offspring than other organisms in the group, so their traits were passed on to more offspring.

B. Such traits are necessary to ensure survival of the species.

C. These traits evolved randomly, and just happened to persist over time.

D. These traits evolve in response to environmental challenges, ensuring that the group will survive any changes in its local living conditions.