Topic 9 -Exploitation of Light

Scientific Method

A systematic approach to investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.

Photosynthesis

The process by which plants convert light energy into chemical energy in the form of glucose.

Phototropism

The growth of a plant towards light.

Heliotropism

The ability of a plant to track the movement of the sun across the sky.

Phytochrome

A photoreceptor that plants use to detect light and its quality.

Photoperiodism

The physiological reaction of organisms to the length of day or night.

Circadian Rhythms

Biological processes that display an endogenous, entrainable oscillation of about 24 hours.

Seed Germination

The process by which a seed develops into a new plant.

Dark Growth Form

A form of growth characterized by elongated stems and small leaves, typically seen in plants growing in low light.

Light Growth Form

A form of growth characterized by shorter stems and larger, greener leaves, typically seen in plants growing in adequate light.

Stomatal Opening

The process by which stomata open to allow gas exchange in plants.

Tritrophic Interactions

Interactions involving three trophic levels, such as plants, herbivores, and their predators.

Abiotic Factors

Non-living environmental factors that can affect organisms, such as light, temperature, and water.

Biotic Factors

Living components of an ecosystem that can affect organisms, including other plants and animals.

Chlorophyll Movement

The process by which chlorophyll-containing organelles (chloroplasts) move within plant cells in response to light.

Seedlings

Young plants that develop from seeds.

Shade Avoidance

The growth response of plants to avoid shade, characterized by elongation and reduced leaf size.

Positive Phototropism

The growth of plant shoots towards a light source.

Negative Phototropism

The growth of plant roots away from a light source.

Germination Conditions

Requirements necessary for seed germination, including light, moisture, and temperature.

Petiole

The stalk that attaches the leaf blade to the stem of the plant.

Daylength

The duration of light a plant receives during a 24-hour cycle.

Flowers and Seasons

The timing and conditions required for flowering are influenced by the seasons and light availability.

Hypocotyl

The part of a seedling below the seed leaves and above the root.

Ethylene

A plant hormone that regulates growth, ripening, and other processes.

Photomorphogenesis

Developmental processes in plants influenced by light.

Cryptochromes

Blue-light photoreceptors that regulate growth and development in plants.

Light Intensity

The amount of light energy reaching a given area.

Light Wavelength

The distance between successive peaks of a wave of light, affecting plant responses.

Light Quality

The specific wavelengths of light that plants can absorb and utilize.

Nuclear Transport

The process by which molecules move between the nucleus and the cytoplasm.

Zea mays

Scientific name for maize, a model organism for studying plant physiology.

Avena sativa

Scientific name for the common oat, used in studies of phototropism.

Homologous Genes

Genes related by descent from a common ancestor.

Deciduous Plants

Plants that lose their leaves seasonally.

Evergreen Plants

Plants that retain their leaves throughout the year.

Phototropic Responses

Movements or growth reactions of plants in response to light direction.

Plant Hormones

Chemicals that regulate physiological processes in plants.

Light-dependent Reactions

Reactions in photosynthesis that require light to produce ATP and NADPH.

Light-independent Reactions

Reactions in photosynthesis that do not require light directly, also known as the Calvin cycle.

Xylem

Tissue responsible for the transport of water in plants.

Phloem

Tissue responsible for the transport of nutrients and sugars in plants.

Abiotic Stress

Stress caused by non-living environmental factors such as drought or extreme temperatures.

Biotic Stress

Stress caused by living factors such as pests or diseases affecting the plants.

Herbivore-Induced Signals

Chemical signals released by plants when attacked by herbivores to attract predators.

Medicinal Properties

Health benefits derived from plants or plant extracts.

Circadian Oscillator

The internal mechanism that controls circadian rhythms in organisms.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Apical Dominance

The phenomenon wherein the central stem of the plant grows more height than the side stems.

Gene Expression

The process by which information from a gene is used to synthesize functional gene products like proteins.

Developmental Plasticity

The ability of a plant to change its growth and development in response to environmental conditions.

Root Shading

Shade experienced by roots from overlying foliage affecting their growth.

Leaf Orientation

The positioning of leaves to maximize light capture for photosynthesis.

Glucosinolates

Natural compounds found in some plants that can deter herbivores.

Transcriptional Regulation

Control of the amount of gene product produced from a given gene.

Phenotype

The observable physical or biochemical characteristics of an organism.

Genotype

The genetic constitution of an individual organism.

Nutrient Uptake

The process by which plants absorb nutrients needed for growth.

Environmental Cues

External signals that trigger physiological responses in plants.

Symbiotic Relationships

Interactions between different biological species that are mutually beneficial.

Pollination

The process by which pollen is transferred from the male anther to the female stigma.

Chloroplast Movement

The relocation of chloroplasts within plant cells in response to light exposure.

Dormancy

A period in the life cycle of a plant wherein growth and development are temporarily halted.

Adaptation

The process through which plants adjust to their environment to enhance survival.

Radial Growth

Growth in a direction that increases the girth of a plant.

Axillary Buds

Buds that develop from the axils of leaves and can grow into new shoots.

Epigenetics

Changes in gene expression that do not involve changes to the underlying DNA sequence.

Apoplast

The network of cell walls and intercellular spaces within a plant.

Symplast

The network of cytoplasm among the cells connected by plasmodesmata.

Root Exudates

Substances secreted by roots into the soil that can influence microbial communities.

Polar Transport

The directional movement of hormones or substances within a plant.

Transpiration

The process of water movement through a plant and its evaporation from aerial parts.

Hydroponics

A method of growing plants using mineral nutrient solutions in water, without soil.

Plant Resilience

The ability of plants to recover from changes or disturbances in their environment.

Plant Ontogeny

The development of a plant from fertilization to maturity.

Secondary Metabolites

Organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism.

Light-Dependent Reactions

The first stage of photosynthesis, occurring in the thylakoid membranes.

Photosynthetic Enzymes

Proteins that facilitate the chemical reactions involved in photosynthesis.

Rosette Plants

Plants that have a circular arrangement of leaves, often close to the ground.

Photoinhibition

A decrease in the photosynthetic rate due to excess light.

Photoprotection

The mechanisms by which plants protect themselves from damage caused by excess sunlight.

red light - 600 nm

Pr (phytochrome red) absorbs ____ light

far red light, 730 nm

Pfr (phytochrome far red) absorbs _____ light

Pr (Phytochrome red)

The inactive phytochrome

Pfr (Phytochrome far red)

The active phytochrome

Pfr

Absorbs far red light and converted back into inactive form (Pr)

Pr

Absorbs red light and converts to the active form (Pfr)

Cytokinin

The hormone that helps plants respond to drought

acid-induced denaturation of cell wall proteins

Auxin enhances cell elongation in all of these ways except