BI.9B

During a class discussion, Olive and Tony were talking about how certain species evolve over time. Which of the following best describes the concept of gradualism in the fossil record?

• Sudden changes in species over a short period

• Slow and steady changes in species over a long period

• No change in species over time

• Random changes in species without a pattern

Answer explanation

Gradualism refers to the idea that species evolve slowly and steadily over long periods, rather than through sudden changes. This concept is best captured by the choice "Slow and steady changes in species over a long period."

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NGSS.MS-LS4-1

During a class discussion, Olive and Noah were talking about how some animals seem to appear suddenly in the fossil record, while others show a slow and steady change over time. What is the primary difference between these two evolutionary patterns?

• Abrupt appearance involves slow changes, while gradualism involves sudden changes.

• Abrupt appearance involves sudden changes, while gradualism involves slow changes.

• Both involve sudden changes in species.

• Both involve slow changes in species.

Answer explanation

The primary difference is that abrupt appearance refers to sudden changes in species, while gradualism describes slow, incremental changes over time. Thus, the correct choice highlights this distinction accurately.

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During a class discussion, Kennedi and Noah were exploring how the concept of stasis is observed in the fossil record. Can you provide an example?

• Stasis is observed when species show no significant change over long periods; for example, the coelacanth fish.

• Stasis is observed when species evolve rapidly; for example, the evolution of horses.

• Stasis is observed when species go extinct suddenly; for example, the dinosaurs.

• Stasis is observed when species migrate to new environments; for example, the Galapagos finches.

Answer explanation

Stasis refers to periods where species exhibit little to no evolutionary change. The coelacanth fish is a prime example, as it has remained relatively unchanged for millions of years, illustrating this concept in the fossil record.

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Tony and Kennedi are studying the fossil record of a particular species that has shown little change over millions of years. They are trying to understand why this species might exhibit stasis. What could be a potential reason?

• Lack of environmental changes and stable ecological niches

• Frequent environmental changes and unstable ecological niches

• High mutation rates and rapid evolution

• Constant migration and adaptation to new environments

Answer explanation

Species may exhibit stasis due to a lack of environmental changes and stable ecological niches, allowing them to thrive without significant evolutionary pressures, leading to minimal morphological changes over time.

During a class discussion, Noah and Olive are learning about the fossil record. Which of the following scenarios best illustrates the concept of abrupt appearance in the fossil record?

• A species gradually changes over millions of years.

• A species appears suddenly in the fossil record with no apparent ancestors.

• A species remains unchanged for a long period.

• A species migrates to a new environment and adapts slowly.

Answer explanation

The correct choice illustrates abrupt appearance as it describes a species that emerges suddenly in the fossil record without any known ancestors, contrasting with gradual changes or adaptations seen in other scenarios.

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Noah and Kennedi are studying the fossil record for their biology project. They want to understand how the fossil record can be used to support the theory of gradualism. What should they look for in the fossil record?

• By showing a continuous and slow change in species morphology over time

• By showing sudden and rapid changes in species morphology

• By showing no change in species morphology over time

• By showing random and unpredictable changes in species morphology

Answer explanation

The fossil record supports gradualism by demonstrating a continuous and slow change in species morphology over time, indicating that evolution occurs through small, incremental changes rather than sudden shifts.

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During a class discussion, Olive and Tony were evaluating the evidence for abrupt appearance in the fossil record. What are the implications of this evidence for evolutionary theory?

• Abrupt appearance suggests that species evolve slowly and predictably.

• Abrupt appearance suggests that species can appear suddenly, challenging gradualism.

• Abrupt appearance suggests that species do not evolve at all.

• Abrupt appearance suggests that species evolve only in isolated environments.

Answer explanation

Abrupt appearance in the fossil record indicates that species can emerge suddenly rather than through gradual changes, which challenges the traditional view of gradualism in evolutionary theory.

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During a class discussion, Tony and Brynlie were asked to identify an example of gradualism in the fossil record. Which of the following did they choose?

• The sudden appearance of flowering plants

• The slow evolution of the horse from small, multi-toed ancestors

• The extinction of the dinosaurs

• The unchanged morphology of the crocodile over millions of years

Answer explanation

The slow evolution of the horse from small, multi-toed ancestors exemplifies gradualism, showing a continuous and gradual change over time, unlike the sudden appearance of flowering plants or the extinction of dinosaurs.

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David and Olive are studying fossils to understand how species evolved over time. How might they use fossil evidence to distinguish between gradualism and abrupt appearance?

• By analyzing the rate of change in species morphology over time

• By examining the color of fossils

• By measuring the size of fossils

• By counting the number of fossils found

Answer explanation

Scientists can distinguish between gradualism and abrupt appearance by analyzing the rate of change in species morphology over time, as this reveals patterns of evolution and helps identify whether changes occurred slowly or suddenly.

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NGSS.MS-LS4-2

Noah and Olive are studying the fossil record for their biology project. They notice that some species seem to appear abruptly in the fossil record. What hypothesis could they propose to explain this phenomenon?

• Rapid environmental changes leading to quick adaptations

• Slow and steady environmental changes

• Lack of any environmental changes

• Constant migration without adaptation

Answer explanation

Rapid environmental changes can create new challenges that force species to adapt quickly, leading to their abrupt appearance in the fossil record. This contrasts with slow changes, which allow for gradual evolution.

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