How new species form
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Animals crossing a barrier in one generation, in two model cases (model data)
case barrier animals crossing flying insects in two valleys open air 30 rodents on two sides of a new lake water 0 Bo compares two model cases. Which case is more likely to lead to speciation, and why?
- The insects, because with 30 crossing, the two groups are cut off from each other
- Neither, because both cases happen in one region of land, so no isolation arises
- The rodents, because any barrier makes a new species at once, whatever the crossing
- The rodents, because with none crossing, alleles are not shared between them
Two plant groups in one model meadow (model data)
plant group chromosomes in each body cell flowering months interbreeds with ancestors? ancestor plants 6 April and May yes new plants 12 April and May no Esme reads a table about one meadow. The new plants cannot interbreed with the ancestor plants. What isolates them?
- Their doubled chromosome number, since place and flowering time are the same
- A barrier in the meadow, since the two groups live apart from one another there
- Their flowering months, since the two groups reproduce at different times
- Nothing yet, since they look like the ancestors and are the same species
Abert and Kaibab squirrels (real facts)
fact value kind of group subspecies forest the same kind of pine forest for both what lies between them the Grand Canyon squirrels studied 60 Abert and 62 Kaibab Jun notes that the squirrels' forests match, yet the two groups are separate subspecies. Which explanation fits?
- Each squirrel changed its body to fit its side of the canyon, which made new species
- The canyon already made them two separate species, so the forests do not matter here
- Groups need different forests to change, so a hidden difference must exist
- The canyon stops alleles moving between them, so each group can change on its own
Cichlids in Lake Apoyeque, Nicaragua (real facts)
fact value age of the crater lake 1800 years time since one cichlid population settled it 100 years populations now 2, with different body forms and diets scientists' view may be at an early stage of speciation Kira sees that two forms arose in about 100 years in one lake. Which statement fits the facts best?
- The two forms may be at an early stage of speciation, not a finished split
- The two forms are already separate species, since 100 years have passed
- The lake's age of 1800 years tells us how long any speciation here must take
- No speciation can start here, since the fish share one lake and no barrier splits it
Thick-leaved plants per 100 on two sides of a river (model data)
group generation 1 generation 2 generation 3 east 40 38 37 west 40 41 42 Luz notes that two groups on opposite sides of a river are nearly alike after 3 generations. No plants cross the river. Which explanation fits?
- Barriers do not matter here, since mutation alone changes groups over time
- The barrier should have made two separate species by now, so something went wrong
- Three generations is little time; groups need longer apart to change much
- The river failed to separate the groups, since alleles still move across it
Notebook
Notes on a river and a mouse population (classmate's notebook), 4 lines. Columns: line, entry. Line 1: A new river splits one mouse population into a north group and a south group. Line 2: No mice cross the river, so alleles stop moving between the groups. Line 3: So the north and south groups were two separate species as soon as the river formed. Line 4: Over many generations each group may gain different alleles and face different conditions.
Milo reads a classmate's notebook about a river and a mouse population. Which line has the mistake?
- Line 2: alleles keep moving between the groups, even though no mice cross the river
- Line 3: a barrier alone does not make species; change takes many generations
- Line 4: the groups should change into two species within a single generation
- Line 1: a river cannot split one mouse population into a north group and a south group
Notebook
Notes on a model plant with extra chromosomes (classmate's notebook), 4 lines. Columns: line, entry. Line 1: A plant species has 6 chromosomes in each body cell. Line 2: An error leaves some offspring with 12 chromosomes in each body cell. Line 3: These new plants can interbreed with their own kind, but only after thousands of generations. Line 4: They can grow in the same meadow as the ancestor plants.
Noah reads a classmate's notebook about a model plant with extra chromosomes. Which line has the mistake?
- Line 2: an error cannot leave offspring with more chromosomes in each body cell
- Line 1: a plant species cannot have 6 chromosomes in each body cell of the plant
- Line 3: the new plants are isolated from the ancestors right away, with no wait
- Line 4: plants with different chromosomes cannot grow in the same meadow together
Notebook
Notes on crater-lake cichlids (classmate's notebook), 4 lines. Columns: line, entry. Line 1: Lake Apoyeque is a crater lake that is 1800 years old. Line 2: Genetic evidence shows one cichlid population settled it about 100 years ago. Line 3: Speciation needs a physical barrier, so these fish cannot be forming new species. Line 4: Two populations with different body forms and diets now live in the lake.
Pia reads a classmate's notebook about crater-lake cichlids. Which line has the mistake?
- Line 2: genetic evidence cannot show when a population settled a lake
- Line 3: speciation can start in one place, without a physical barrier
- Line 4: two populations cannot have different diets and body forms
- Line 1: a crater lake is not a place where a population can settle
Two spotted owl subspecies (real facts)
subspecies where it lives climate northern spotted owl the north cooler than the south Mexican spotted owl the south warmer than the north Ren judges a claim about northern and Mexican spotted owls, which are subspecies in separate places with different climates. Which claim and reason fit best?
- Each owl will turn into a new species, since the climate where it lives changes it
- The owls cannot change, since subspecies are fixed groups that stay the same
- The owls may be heading toward speciation, since climates can favor different traits
- The owls are two separate species, since they live far apart from each other
Flowering months of two model plant groups in one meadow (model data)
group first month last month group A March April group B June July Zee judges a claim about two model plant groups that share one meadow. Which claim and reason fit best?
- Timing isolation works for animals, but plants cannot reproduce on a schedule
- Flowering times cannot isolate the groups, since both groups share one meadow
- A barrier is needed to isolate the groups, since a single meadow cannot isolate them
- Timing can isolate the groups in one meadow, since they flower at different times