Biology Keystone Module 2

Mitosis and meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis?

• Meiosis is a multi-step process.

• Mitosis occurs only in eukaryotic cells.

• Meiosis is used in the repair of an organism.

• Mitosis produces genetically identical daughter cells.

Answer explanation

Mitosis produces genetically identical daughter cells, while meiosis results in genetically diverse cells. This distinction is crucial for understanding their different roles in growth and reproduction.

Tags

NGSS.HS-LS1-4

Which event most likely occurs next in mitosis?

• The chromatin condenses.

• The nuclear envelope dissolves.

• The chromosomes double in number.

• The cell membrane pinches inward to divide the cytoplasm.

Answer explanation

The cell membrane pinches inward to divide the cytoplasm, completing cytokinesis after mitosis. This follows the separation of chromosomes, making it the next logical event.

Tags

NGSS.HS-LS1-4

A scientist observes that a certain trait is determined by a single allele. An organism inherited one version of the trait from one parent and another version from the other parent. Both versions of the trait are expressed in the phenotype of the offspring. Which pattern of inheritance best classifies the observed trait?

• dominance

• sex-linkage

• co-dominance

• incomplete dominance

Answer explanation

The trait is expressed with both versions visible in the phenotype, indicating co-dominance. In co-dominance, both alleles contribute equally to the phenotype, unlike dominance where one allele masks the other.

A researcher observing an ecosystem describes the amount of sunlight, precipitation, and type of soil present. Which factors is the researcher most likely describing?

• biotic factors in a forest

• biotic factors in a tundra

• abiotic factors in a prairie

• abiotic factors in an ocean

Answer explanation

The researcher describes sunlight, precipitation, and soil type, which are non-living components of the environment. These are abiotic factors, and since they are typically associated with prairies, the correct choice is abiotic factors in a prairie.

Tags

NGSS.MS-LS2-3

 Which term best classifies all of the observations?  Observations:  two grey wolves, five moose, several species of conifer trees, large granite rock and shallow pond.

• population

• food chain

• ecosystem

• community

Answer explanation

The observations include living organisms (wolves, moose) and non-living elements (trees, rock, pond), which together form an ecosystem. An ecosystem encompasses all interacting components in a specific area.

Tags

NGSS.MS-LS2-3

A species of snapping turtles has a tongue that resembles a worm. The tongue is used to attract small fish. Which best describes the interaction between the fish and the snapping turtle?

• predation

• symbiosis

• parasitism

• competition

Answer explanation

The interaction between the fish and the snapping turtle is best described as predation. The turtle uses its worm-like tongue to lure and capture fish, indicating a predator-prey relationship.

Which sequence correctly describes the flow of energy between organisms in the marine food web?

• from seals to penguins to krill

• from whales to krill to small fish

• from sea birds to seals to penguins

• from small fish to penguins to seals

Answer explanation

The correct sequence is from small fish to penguins to seals, as it follows the energy flow in the marine food web. Small fish are prey for penguins, which in turn are preyed upon by seals, illustrating the predator-prey relationship.

Tags

NGSS.MS-LS2-2

NGSS.MS-LS2-3

An exchange of genetic material between homologous chromosomes during Prophase I of meiosis; contributes to the genetic variability in gametes and in offspring

• Crossing over

• Nondisjunction

• Gamete

• Cytokinesis

Answer explanation

Crossing over is the exchange of genetic material between homologous chromosomes during Prophase I of meiosis, leading to increased genetic variability in gametes and offspring.

Which of these is most likely to be an abiotic component of a temperate grassland ecosystem?

• a layer of frozen soil called permafrost

• a population of large grazing mammals

• annual precipitation of 20cm to 100cm

• a temperature range from -40^oC to 10^oC

Answer explanation

Annual precipitation of 20cm to 100cm is an abiotic factor that influences the temperate grassland ecosystem, providing necessary moisture for plant growth. The other options are either biotic or not typical for this ecosystem.

Tags

NGSS.MS-ESS2-4

NGSS.MS-ESS2-5

A section of a gene has the following sequence of nitrogenous bases:  TGACAT.  If a frame-shift mutation occurs in this section, which of the following could be the mRNA strand coded from it?

• ACTGTA

• ACUGUA

• ACTGTTA

• ACUGUUA

Answer explanation

A frame-shift mutation alters the reading frame, changing the sequence. The original sequence TGACAT translates to mRNA as ACUGUA. After a frame-shift, the correct mRNA is ACUGUUA, as it reflects the new reading frame.

Tags

NGSS.HS-LS3-2