Plant Evolution

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AP Biology › Plant Evolution

Questions 1 - 10
1

Which structures did not evolve after plants emerged onto land?

Cell walls

Seeds

Stomata

Waxy cuticles

Vascular transport

Explanation

Cell walls were present in plant cells before the transition to land. Seeds, stomata, waxy cuticles, and vascular transport all evolved to reduce water loss and circulate water to all areas of the plant. Water loss and circulation were not an issue before the transition to land; plants were forced to adapt these traits in order to survive in a terrestrial environment.

2

Which structures did not evolve after plants emerged onto land?

Cell walls

Seeds

Stomata

Waxy cuticles

Vascular transport

Explanation

Cell walls were present in plant cells before the transition to land. Seeds, stomata, waxy cuticles, and vascular transport all evolved to reduce water loss and circulate water to all areas of the plant. Water loss and circulation were not an issue before the transition to land; plants were forced to adapt these traits in order to survive in a terrestrial environment.

3

As plants moved from water to land, they developed structures and lifestyles better suited to life in their new environment. Which of the following is not an example of these adaptations?

Decrease in rigidity

Cuticle

Vascular tissue

Roots

Increase in vertical height

Explanation

Plants developed more rigid structures to help maintain their growth on land as opposed to water.

Waxy cuticles developed to help reduce water loss/desiccation. Roots allowed plants greater access to water, as well as provided anchoring to the ground; this allowed plants to grow taller. Vascular tissue facilitated transport of water and nutrients to all parts of the plant. Stomata helped with gas exchange.

4

As plants moved from water to land, they developed structures and lifestyles better suited to life in their new environment. Which of the following is not an example of these adaptations?

Decrease in rigidity

Cuticle

Vascular tissue

Roots

Increase in vertical height

Explanation

Plants developed more rigid structures to help maintain their growth on land as opposed to water.

Waxy cuticles developed to help reduce water loss/desiccation. Roots allowed plants greater access to water, as well as provided anchoring to the ground; this allowed plants to grow taller. Vascular tissue facilitated transport of water and nutrients to all parts of the plant. Stomata helped with gas exchange.

5

How is it believed that plants first became photosynthetic?

An ancestor of modern plants internalized a photosynthetic prokaryote through phagocytosis

A vacuole became specialized for photosynthesis

The origin of the chloroplast is still largely unknown

The chloroplast was a cluster of synthesized proteins, which evolved over time

Explanation

The chloroplast is believed to have evolved from photosynthetic bacteria that formed a mutualistic symbiotic relationship with an ancestor of plants through endosymbiosis. There is lots of evidence supporting the endosymbiotic theory, which is based on the principle of one organism phagocytosing another, resulting in mutualism.

6

How is it believed that plants first became photosynthetic?

An ancestor of modern plants internalized a photosynthetic prokaryote through phagocytosis

A vacuole became specialized for photosynthesis

The origin of the chloroplast is still largely unknown

The chloroplast was a cluster of synthesized proteins, which evolved over time

Explanation

The chloroplast is believed to have evolved from photosynthetic bacteria that formed a mutualistic symbiotic relationship with an ancestor of plants through endosymbiosis. There is lots of evidence supporting the endosymbiotic theory, which is based on the principle of one organism phagocytosing another, resulting in mutualism.

7

Which is of the following is not an adaptation/modification that enabled plants to move from aquatic to terrestrial environments as they evolved?

Thylakoid membranes

Cutin

Stomata

Roots and root hairs

Explanation

Thylakoid membranes are found within chloroplasts, which are used for photosynthesis. Plants found in both aquatic and terrestrial environments photosynthesize, so these membranes cannot be considered adaptations uniquely benefiting terrestrial plants.

Comparatively, cutin is a waxy coating found on various parts of plants that helps prevent water loss when exposed to air. Stomata are tiny openings in the epidermis of plants that allow for the exchange of carbon dioxide and oxygen while minimizing water loss. Roots and root hairs allow plants to absorb nutrients and water from the soil. Water loss was the primary challenge plants faced when moving from aquatic to terrestrial environments; cutin, stomata, roots, and root hairs all help terrestrial plants absorb and conserve water.

8

Which is of the following is not an adaptation/modification that enabled plants to move from aquatic to terrestrial environments as they evolved?

Thylakoid membranes

Cutin

Stomata

Roots and root hairs

Explanation

Thylakoid membranes are found within chloroplasts, which are used for photosynthesis. Plants found in both aquatic and terrestrial environments photosynthesize, so these membranes cannot be considered adaptations uniquely benefiting terrestrial plants.

Comparatively, cutin is a waxy coating found on various parts of plants that helps prevent water loss when exposed to air. Stomata are tiny openings in the epidermis of plants that allow for the exchange of carbon dioxide and oxygen while minimizing water loss. Roots and root hairs allow plants to absorb nutrients and water from the soil. Water loss was the primary challenge plants faced when moving from aquatic to terrestrial environments; cutin, stomata, roots, and root hairs all help terrestrial plants absorb and conserve water.

9

Which of the following refers to the principle of alternation of generations in plants?

A life cycle that includes a multicellular haploid stage

The differences between a tree and a seed

Gamete-producing sporophytes

A life cycle which includes a unicellular haploid stage

The need for external pollinators

Explanation

Plants have a multicellular haploid stage called the gametophyte. Gametophytes () produce gametes () through mitosis, which combine to produce a zygote (). The zygote grows into a multicellular, diploid sporophyte (), which produces spores () through meiosis. Those spores give rise to multicellular gametophytes.

10

Which of the following refers to the principle of alternation of generations in plants?

A life cycle that includes a multicellular haploid stage

The differences between a tree and a seed

Gamete-producing sporophytes

A life cycle which includes a unicellular haploid stage

The need for external pollinators

Explanation

Plants have a multicellular haploid stage called the gametophyte. Gametophytes () produce gametes () through mitosis, which combine to produce a zygote (). The zygote grows into a multicellular, diploid sporophyte (), which produces spores () through meiosis. Those spores give rise to multicellular gametophytes.

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