Plant Biology: Photosynthesis, Respiration, and Transpiration

Vocabulary flashcards covering leaf adaptations, photosynthesis, cellular respiration, cell theory, and the factors influencing transpiration rate.

Autotrophic

Describes organisms, such as all plants, that make their own food.

Photosynthesis

The process by which plants combine carbon dioxide and water to make glucose using light energy from the sun, releasing oxygen as a waste product.

Chlorophyll

A green pigment contained in chloroplasts that absorbs light energy for photosynthesis and gives most plants their green color.

Chloroplasts

Specialized units in leaf cells containing chlorophyll that serve as the site where photosynthesis occurs.

Cuticle

A waxy layer covering the surface of a leaf that prevents water loss by evaporation.

Stomata

Pores in the outer surface of a leaf that allow air and gases to enter and leave.

Guard cells

A pair of cells surrounding each stoma that open or close the pore to control airflow and prevent water loss.

Epidermis

The outermost layer of cells in a leaf.

Palisade mesophyll

A tightly packed layer of cells positioned just below the upper epidermis that contains many chloroplasts to receive maximum light.

Spongy mesophyll

A layer of loosely packed cells located below the palisade mesophyll that allows air to circulate freely inside the leaf.

Vascular bundle

A network of leaf veins that carries water and minerals into the leaf and transports sugars produced by photosynthesis away.

Respiration

The process in living cells that uses oxygen to break down glucose to extract energy, producing carbon dioxide and water as waste products.

Mitochondria

Specialized cell structures in all cells where respiration takes place to release energy.

Cell theory

The biological theory associated with Robert Hooke stating that all living things are made of cells, cells are the basic unit of life, and cells come from pre-existing cells.

Xylem vessels

Tubes located in the centre of roots and stems through which water is pulled up to the leaves.

Cohesive

The property of water molecules sticking together, allowing a continuous column of water to be pulled up through a plant.

Transpiration

The process of water evaporating from the leaves of a plant, pulling a continuous column of water up from the roots to replace it.

Transpiration stream

The path of water moving from the soil into the roots, up through the stem xylem to the leaf stomata, and out into the atmosphere.

Transpiration rate

The speed at which water moves through a plant, which is directly controlled by the rate of evaporation from the leaves.

Humidity

The amount of water vapour held in the air; high levels reduce evaporation and decrease the transpiration rate.

Autotrophic

The property of organisms, such as all plants, that make their own food.

Photosynthesis

The process where plants combine carbon dioxide and water using light energy from the sun to produce glucose and release oxygen as a waste product, summarized by $\text{carbon dioxide} + \text{water} \rightarrow \text{glucose} + \text{oxygen}$.

Chlorophyll

A green pigment contained in chloroplasts that collects light energy for photosynthesis and gives most plants their green color.

Chloroplasts

Special units contained in leaf cells that house chlorophyll and serve as the site where photosynthesis occurs.

Glucose

A simple sugar produced during photosynthesis that is used immediately for energy, used to make growth substances, or converted to starch for storage.

Cuticle

A waxy layer over the leaf surface that prevents water loss from evaporation, but also prevents gas exchange.

Stomata

Pores in the outer surface of a leaf (singular: stoma) that allow air and gases to enter and leave.

Guard cells

A pair of cells controlling each stoma that open or close to regulate airflow and prevent water loss when necessary.

Epidermis

The outermost layer of cells in a leaf.

Palisade mesophyll

A tightly packed layer of cells positioned directly below the epidermis that contains many chloroplasts to receive maximum light.

Spongy mesophyll

A layer of loosely packed cells below the palisade mesophyll that allows air, oxygen, and carbon dioxide to circulate freely.

Vascular bundle

A network of leaf veins that carries water and minerals into the leaf and carries sugars produced by photosynthesis away.

Respiration

The process in cells that uses oxygen to break down glucose into carbon dioxide and water to release energy, summarized by $\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}$.

Mitochondria

Specialised structures inside cells where respiration takes place.

Cell theory

A biological theory associated with Robert hook stating that all living things are made of cells, cells are the basic unit of life, and cells come from pre-existing cells.

Xylem vessels

Vessels at the centre of the root and stem that receive water from the soil and transport it upward through the plant.

Transpiration

The process by which water evaporates from a plant's leaves into the atmosphere, pulling a continuous column of water up through the plant.

Transpiration rate

The speed at which water moves through a plant, which is directly controlled by the rate of evaporation from the leaves.

Humidity effect on transpiration

High humidity decreases transpiration rate because the air already contains high levels of water vapour and cannot hold much more, reducing evaporation.

Wind effect on transpiration

Wind increases transpiration rate by moving saturated air away from the leaf surface, allowing more water to evaporate.