Chapter 8: Plant Systems: Gas Exchange and Transport Systems Flashcards
What does vascular mean?
De scribes vessels that conduct fluid
What is the epidermis on a plant?
The surface layer of cells in an organism
What are stomata?
A controlled opening found in leaves and young stems that controls the movement of gases into and out of a plant
What are guard cells?
A pair of crescent-shaped cells that enable the opening and closing of stomata
What conditions cause stomata to open?
In wet conditions, the guard cells swell and become rigid, opening the stomata
What conditions cause the stomata to close?
Dry conditions, the guard cells lose water they become soft and fall closed, due to this, gases cannot enter and leave
What do pineapples, cacti and orchids do to enable photosynthesis, even when the stomata are closed?
They open their stomata during the cool evening and store carbon dioxcide
What is mesophyll?
A chloroplast-containing cell in plant leaves that performs photosynthesis
What does tugidity?
The state of being swollen with water, which usually causes the cell to become rigid
What is the cuticle?
A thin, transparent layer of wax on the outside of a leaf’s epidermis to reduce water loss
What are the two types of mesophyll cells?
Palisade mesophyll and spongy mesophyll
What is palisade mesophyll?
A densely packed layer of elongated cells that have many chloroplasts for photosynthesis
What is spongy mesophyll?
A loosely arranged layer of irregularly shaped cells that have a few chloroplasts for photosynthesis and plenty of air spaces
What are the two type of vascular tissues in a plant?
Xylem and phloem
What is xylem?
The vascular tissue in plants, consisting of dead cells, responsible for the bulk transport of water and nutrients
What is phloem?
The vascular tissue in plants, consisting of living cells, responsible for the transport of sugars from leaves to the rest of the plant
What are the two types of cells that make up xylem in a plant?
Tracheids and vessel elements
What are tracheids?
A dead elongated cell that forms, the unspecialised part of the xylem of plants
What are vessel elements?
A dead cell that is perforated at each end and stacked vertically, forming the specialised part of the xylem in flowering plants, almost a straw
Which is more effective: tracheids or vessel elements?
Vessel elements due to their ‘straw like’ strucutre, however, this adaptation is only foun din flowering plants (angiosperms)
What are the two types of phloem cells?
Sieve tube cells and companion cells
What is a seive tube cell?
A long, tubular plant cell without a nucleus that form seive tubes, the main component of the phloem
What is a companion cell?
A specialised plant cell situated beside the seive tubes in the phloem, which provides most of the cell dunctions for the seive tube cells
What are sieve plates?
The tough cellulose walls between sieve tube cells that contain pores to allow the cytoplasm to flow between cells
What are plasmodesmata?
A tiny channel through plant cell walls that allows communication between cells by sharing cytoplasm
What are the two main root forms?
Taproot and fibrous root
What is a taproot?
A large main root deep underground for stability and long-term water supply
What is a fibrous root?
A thin, branching root that spreads along the upper layers of soil for rapid colonisation and surface water uptake
What is root hair?
A thin extension of a root epidermal cell that greatly increases the cell’s surface area
What is root pressure?
The prussure, caused by the uptake of water in the roots, that forces water furhter up the stem
What are monocotyledons (monocots)?
A flowering plant with a number of characteristics, including scattered arrangement of vascular bundles in the stem
What are dicotyledons (dicots)?
A flowering plant with a number characteristics, including a ringed arrangement of vascular bundles in the stem
What is adhesion?
The force of attraction between water molecules and the molecules that make up the sides of the tube
What is cohesion?
The force of attraction between water molecules
What is transpiration?
The loss of water from plants through evaporation
What is transpiration stream?
A continuous column of water that moves up the stem of the plant
What is transpirational pull?
The force arising from the evaporation of water from leaves that draws water up the xylem
What factors can increase the rate of transpiration?
High air temperatures, low humidity, wind and long days with strong sunlight
What are some adaptations to reduce water loss?
Thick waxy leaves, minimal stomata, spines
What factors can decrease the rate of transpiration?
Low air temperatures, high humdity, stifled airflow and short days with weak sunlight
What is translocation?
The bulk movement of substances during metabolic reactions
