Biology - Nutrition in Plants

- nutrition

process by which living organisms obtain food

- photosynthesis

the process by which green plants convert carbon dioxide and water into glucose by using sunlight energy absorbed by chlorophyll in chloroplasts

- What is the equation for photosynthesis?

6H₂O (l) + 6CO₂ (g) → C₆H₁₂O₆ + 6O₂

- What conditions are necessary for photosynthesis? (6)

Carbon dioxide; Water; Sunlight energy; Chlorophyll; Enzymes (in chloroplasts); Optimum temperature for enzymes

- Describe the light stage of photosynthesis

In the light stage, the light energy absorbed by chlorophyll is used to split water molecules into hydrogen and oxygen — releasing oxygen as a waste product

- What conditions are necessary for the light stage of photosynthesis to occur? (3)

Light, chlorophyll and water

- evolution of oxygen

fundamental process in which oxygen is created and released into the atmosphere as a consequence of photosynthesis

- Describe the dark stage of photosynthesis

In the dark stage, the hydrogen atoms produced in the light stage reduce the carbon dioxide molecules forming glucose via enzymes

- What conditions are necessary for the dark stage of photosynthesis to occur? (3)

Hydrogen atoms, carbon dioxide molecules, enzymes

- chlorophyll

green pigment found in chloroplasts that absorbs light which is used as energy in photosynthesis

- chloroplast

a rod-shaped organelle that produces chlorophyll and houses photosynthesis

- What are the four main environmental factors affecting the photosynthesis rate? (4)

Light; carbon dioxide; temperature and water

- How does light affect the photosynthetic rate? (2)

Light limits the rate between dusk and dawn, and during the winter months in temperate climates due to the lack of light for energy

- How does temperature affect the photosynthetic rate?

Temperature limits the rate during the winter months — destabilizing enzymes used to assemble glucose

- How does water affect the photosynthetic rate? (2)

Water limits the rate during the dry season in tropical climates and when the ground is frozen in temperate climates

- How does carbon dioxide limit the photosynthetic rate?

It limits the rate during the day in most climates since the concentration of carbon dioxide in the air is very low

- glucose

a sugar that is used as a source of energy in the plant

- Where is glucose found/used in the plant? (4)

In the leaf cells in respiration; Condensed into starch for ease of storage; Converted into other organic substances; Converted into sucrose

- Where is sucrose found/used in the plant? (5)

Reconversion into glucose for respiration; Conversion into cellulose to make cell walls in growing plants; As starch for storage; Converted into amino acids and proteins by the addition of nitrates and sulfates; As lipids in seeds

• Label this diagram (6)

A-apex; B-midrib; C-margin; D-vein; E-petiole; F-lamina

- apex

the protruding part of the leaf

- margin

the outline of a leaf blade

- lamina

flat, typically green, expanded part of the leaf blade

- midrib

the central, thicker, linear structure, which runs through the lamina

- vein (leaf)

small channels made of vascular tissue that are responsible for transporting minerals and water throughout the leaf

- petiole

stalk that attaches a leaf to the plant stem

- Briefly describe the external adaptions made by the leaf to maximize photosynthesis (4)

The lamina is broadly held out flat by veins to increase surface area for absorption; Lamina is thin so that sunlight energy and carbon dioxide can easily reach all cells; Laminas are usually held 90° to the sunlight — maximizing its exposure to the sunlight; Laminae are spaced out around stems — maximizing each one’s exposure to the sunlight

• Label this diagram (9)

A-midrib; B-xylem tissue; C-vein; D-upper epidermis; E-palisade mesophyll layer; F-spongy mesophyll layer; G-stoma; H-lower epidermis; I-phloem tissue

• Label this diagram (13)

A-chloroplast; B-wavy cuticle; C-upper epidermis; D-palisade mesophyll layer; E-spongy mesophyll layer; T-lower epidermis; F-guard cell; G-stomatal pore; H-stomata; I-companion cell; J-phloem sieve tube; K-xylem vessel; L-vein

- waxy cuticle

a waxy, waterproof layer which prevents water from leaving the leaf

- palisade mesophyll cells

plant cells found beneath the upper epidermis of the leaf responsible for absorbing a majority of the sunlight for photosynthesis

- spongy mesophyll cells

plant cells which facilitate gaseous exchange for photosynthesis and aid the palisade cells in absorbing light

- guard cells

plant cells which have adapted their structure to open and close stomatal pores when they are turgid or not, respectively

- stomatal pore

pores on the surface of leaves that facilitate the gaseous exchange for photosynthesis

- xylem cells

plant cells which are responsible for transporting water across the plant

- phloem cells

plant cells which are responsible for transporting food substances across the plant

- Briefly describe the internal adaptations made by the leaf to maximize photosynthesis (7)

Waxy cuticles prevent the loss of water; Stomatal pores facilitate gaseous exchange; Palisade mesophyll cells house a majority of the chloroplasts for photosynthesis; Palisade mesophyll cells arrange themselves at 90° to allow chloroplasts to concentrate at the top of the cells in dim light; Spongy mesophyll cells are irregularly shaped in order to house gaseous exchange in intercellular spaces; Xylem vessels supply mesophyll cells with water and mineral ions for their processes; Phloem tubes transport glucose from photosynthesis to other parts of the plant

- nitrogen

a mineral used to form chlorophyll and make proteins in plants

- In what form is nitrogen found in the plant, and what are the results of its deficiency? (1/3)

Nitrate ions/poor growth; chlorosis; underdeveloped leaves

- magnesium

a mineral used to form chlorophyll in plants

- In what form is magnesium found in the plant, and what is the result of its deficiency? (1/1)

Magnesium ions; Chlorosis

- phosphorus

a mineral used to make ATP and some proteins

- In what form is phosphorus found in the plant, and what are the results of its deficiency? (1/3)

Phosphate ions/dull, purple-green leaves with curly brown edges; Poor root growth; Stunted growth

- potassium

a mineral used to help maintain the correct salt balance in plant cells and to help in photosynthesis

- In what form is potassium found in the plant, and what are the results of its deficiency? (1/2)

Potassium ions/yellow-brown margins and brown spots; Premature death of leaves

- sulfur

a mineral used to make proteins in plants

- In what form is sulfur found in the plant, and what are the results of its deficiency? (1/2)

Sulphate ions/Poor growth; Chlorosis

- calcium

a mineral used to make cell walls in the tips of growing roots and shoots

- In what form is calcium found in the plant, and what are the results of its deficiency? (1/3)

Calcium ions/Poor, stunted growth; Death of the growing tips of roots and shoots; Poor bud development

- chlorosis

yellowing of normally green leaves due to lack of chlorophyll