B3 Gas exchange in plants

Which cell type in the leaf is packed with chloroplasts for photosynthesis?

• Palisade Mesophyll
• Spongy Mesophyll
• Guard Cells
• Epidermis

Answer explanation

Palisade mesophyll cells are packed with chloroplasts and are specialized for photosynthesis. Spongy mesophyll cells, while also containing chloroplasts, are more involved in gas exchange. Guard cells regulate stomata, and the epidermis provides protection.

Tags

NGSS.MS-LS1-6

Which structure in the leaf is primarily responsible for gas exchange?

• Stomata
• Vascular Tissue
• Mesophyll Tissue
• Guard Cells

Answer explanation

Stomata are tiny pores that facilitate gas exchange. Vascular tissue transports nutrients, mesophyll tissue contains photosynthetic cells, and guard cells regulate stomatal opening.

Tags

NGSS.MS-LS1-6

What is the primary function of the spongy mesophyll?

• Gas exchange
• Photosynthesis
• Water transport
• Nutrient storage

Answer explanation

The spongy mesophyll facilitates gas exchange with its air spaces. While it does participate in photosynthesis, its structure is optimized for gas movement. Water transport and nutrient storage are handled by other tissues.

Tags

NGSS.MS-LS1-6

Which cells regulate the opening and closing of stomata?

• Guard Cells
• Palisade Cells
• Epidermal Cells
• Spongy Cells

Answer explanation

Guard cells are responsible for regulating stomatal openings through changes in turgor pressure. Palisade and spongy cells are involved in photosynthesis and gas exchange, while epidermal cells protect the leaf surface.

What happens to guard cells when they become turgid?

• Stomata open
• Stomata close
• Water is lost
• Photosynthesis stops

Answer explanation

When guard cells become turgid, they swell and cause the stomata to open, allowing for gas exchange. When they lose turgor, the stomata close. Water loss and photosynthesis are related processes but not directly affected by turgidity alone.

Which part of the leaf contains xylem and phloem?

• Vascular Tissue
• Epidermis
• Mesophyll
• Stomata

Answer explanation

Vascular tissue contains xylem and phloem, which transport water, nutrients, and food. The epidermis protects, the mesophyll aids in photosynthesis and gas exchange, and stomata facilitate gas exchange.

Which leaf adaptation reduces water loss?

• Waxy Cuticle
• Large Surface Area
• Spongy Mesophyll
• Air Spaces

Answer explanation

The waxy cuticle forms an impermeable barrier to reduce water loss while allowing gases to pass through stomata. A large surface area and air spaces are adaptations for gas exchange, not water conservation.

Which environmental factor does NOT affect transpiration?

• Soil pH
• Temperature
• Humidity
• Wind

Answer explanation

Soil pH does not directly affect transpiration. Temperature, humidity, and wind all influence the rate of water vapor loss from leaves.

What is the process called when water vapor is lost from leaves through stomata?

The _______ mesophyll provides a large surface area for gas exchange.

Answer explanation

The spongy mesophyll, with its air spaces, provides a large surface area for gas exchange. This structure enhances the movement of carbon dioxide and oxygen within the leaf.