Unit C: Section 3.0 Flashcards
What are the advantages and disadvantages of having a large structure?
- Division of labour
- Size
- Interdependence of cells
How is division of labour an advantage?
-Specialized cells perform more efficiently
How is size a disadvantage?
-The surface area to volume ratio and the related rate of diffusion restricts the size of unicellular organisms
How is size an advantage?
- In multicellular organisms, internal support structures allow for the efficient exchange of materials
- These permit the organisms to grow a larger size
How is the interdependence of cells an advantage in multi-cellular organisms?
-If one cell dies the organism can still function
How is the interdependence of cells a disadvantage in multi-cellular organisms?
If one cell malfunction it could be possible that as it increases the whole organism could suffer
What are tissues?
Groups of cells performing the same function together
What are organs?
Tissues contributing to the same function
What are Systems?
A set of organs that perform a function
What are the 2 organ systems of a plant?
- Shoot System
- Root System
What is the shoot system?
Every part of the plant above the ground
What is included in the shoot system of a plant?
Stem Leaves Buds Flowers Fruits *Tubers*
What are tubers?
Enlarged, underground stem that stores food
What is the root system?
Every part of the plant that is underground
What do cells divide for in plants?
The growth of new tissue and repair of damaged tissue
What is mitosis?
The process of cell division that allows growth and repair. One cell literally divides into 2
What are meristems?
Regions in plants where cell division occurs
What are the 4 types of tissues in plants?
- Dermal/Epidermis tissue
- Ground tissue
- Vascular tissue
- Phloem tissue
What is Dermal/Epidermis tissue?
-The outer layers of cells that covers all non-woody plants
How many cells thick is the Dermal/Epidermal tissue?
1 cell layer thick
What is the Dermal/Epidermal Tissue responsible for?
The exchange of matter and gasses in and out of the plant
What is the Epidermis in woody plants?
It is replaced by cork and bark during the secondary growth stage and development
What system is the Dermal tissue a part of?
The Shoot System
What does the Dermal tissue do in the shoot system?
- Primarily involved in gas exchange of carbon dioxide and oxygen
- Protects plants from disease
What do the cells of the leave secrete?
A waxy substance called the cuticle
What does the cuticle do?
- Resists attack from micro-organisms
- Helps to reduce water loss from the plant
What is Dermal tissue in the root system responsible for?
Responsible for the uptake of water and mineral salts from the soil
What is the layer of tissue underneath the epidermis called?
Ground tissue
Which tissue makes up the majority of the plant?
Ground tissue
What does ground tissue do in the stem?
It provides strength and support for the plant
What does ground tissue do in the roots?
It is involved in food and water storage
What does occurs in ground tissue in leaves?
Photosynthesis occurs
How the cells in ground tissue arranged?
They are loosely packed together
How does ground tissue help with diffusion?
Because they are loosely packed together the large spaces allows gas to diffuse rapidly
What is Vascular tissue responsible for?
It is responsible for the transport of materials throughout the plant
What are the 2 types of vascular tissue?
Xylem tissue
Phloem tissue
What does Xylem tissue do?
Moves water and dissolved minerals from the roots up the stem to the leaves
What are the substances that they Xylem tissue transports used for?
Photosynthesis
What does Xylem tissue look like?
Thick-walled tubes of varying diameters
What is the thickening of Xylem tube walls the result of?
Cellulose and lignin being deposited in the cell wall
How does Xylem tissue come to be?
- As cylindrical cells mature, they fuse together and the walls at each end become perforated
- As a result, the contents of the cytoplasm break down and the cells die
- Leaving non-living cell walls attachted to each other
Is the Xylem tissue living?
No
What does Phloem tissue do?
Transports sucrose and other dissolved sugars from the leaves to other parts of the plant cell
What is Phloem formed from?
From individual long sieve tube cells
What do sieve tube cells have?
Perforated walls through which cytoplasm extends
What is interesting about Sieve tube cells?
They remain alive but lose their nuclei
What are Sieve tube cells connected to?
Companion cells
What do companion cells do?
They direct the other cells cellular activities
What are the sugars transported by for?
They are used to provide energy for cellular processes such as protein manufacture
What does cellulose form?
Fibrous structures for strength and support and may become associated with the formation of wood
How are the sugars in plants stored?
As starch in roots, stems, or leaves
What type of cells are root hairs?
Specialized cells
What are root hairs?
Hair like projects on cells that are apart of the root system that increase surface area for the absorption of water
What does the lower epidermal surface of leaves produce?
Guard cells that form tiny pores called stomata for gas exchange
What is interesting about guard cells?
They are the only cells in the epidermis that contain chloroplasts
Which place has more stomata? The upper epidermis or the lower epidermis?
The lower epidermis
Why does the upper epidermis have fewer stomata?
So that there is less water loss
What are the 3 main types of tissue?
Thermal
Ground
Vascular
What is the green pigment in chloroplasts called?
Chlorophyll
Where are cells containing chloroplasts found?
In the ground tissue of leaves and sometimes stems
What is the organelle where a plant carries out photosynthesis called?
Chloroplasts
Where does carbon dioxide for photosynthesis come from?
Air
Water
Soil
What is the word formula for photosynthesis?
carbon dioxide + water —> glucose + oxygen
What are the reactants for photosynthesis?
Water and Carbon dioxide
What are the products of photosynthesis?
Glucose and Oxygen
What happens in photosynthesis?
Light energy is absorbed by the chlorophyll and converted into chemical energy
Where is the chemical energy from photosynthesis stored?
In the molecules of glucose
What are not considered to be reactants in photosynthesis?
Light and chlorophyll
What does cytoplasmic streaming do?
Circulates materials and speeds of their distribution within the cell
What is the light energy in photosynthesis stored as?
Chemical energy within glucose
Where does cellular respiration happen?
It begins in the cytoplasm but is completed in the mitochondria
What is the word formula for cellular respiration?
glucose + oxygen —> carbon dioxide + water + energy
What process of the plant only occurs in the day?
Photosynthesis
How do Stomata work?
They open into air chambers that connect with the cells of the ground tissue
How do carbon dioxide and oxygen leave and enter the leaf?
Through diffusion from the Stoma
Where are the majority of Stoma found?
On the underside of a leaf next to epidermal cells
What is the order of tissue on plants?
Cuticle
Epidermis
Ground
What are stomata made of?
Guard cells
How do guard cells work?
They swell up to open the stomata and shrink away to close the stomata
How do Stoma a work?
Light striking the leaf triggers the guard cells to accumulate potassium ions by active transport and as a result, water enters by osmosis and they swell up
What are guard cells function?
- To allow materials in and out when necessary
- Protect leaves from losing too much water
What is transpiration?
The process of water vapor leaving the leaf
Why would a plant have less Stoma?
To adapt to living in a hot dry climate with low humidity
What tissue is between the upper epidermis and the lower epidermis?
Specialized tissue called mesophyll
What are the types of mesophyll/ground tissue?
- Palisade tissue cells
- Spongy mesophyll tissue
Where are palisade tissue cells found?
Just below the upper epidermis
What do palisade tissue cells look like?
Long, rigid, rectangular cells that are tightly packed and arranged so that a large number of cells are exposed to the suns rays
What are the palisade tissue cells responsible for?
They are responsible for photosynthesis, so they have many chloroplasts in them
Where are the spongy mesophyll tissue cells found?
In between the palisade tissue cells and the epidermis tissue
What do the spongy mesophyll tissue cells look like?
Loosely packed, irregularly shaped, and less rigid
What is the primary function of the spongy mesophyll tissue?
Gas exchange by diffusion throughout the leaf. They will move oxygen towards the stomata and carbon dioxide toward that palisade cells
What are leaf veins?
The network of vascular tissue running through it
What is a vascular bundle?
The network of Xylem and Phloem bunched together
Where can diffusion of gasses other than the leaf happen in plants?
Pores along the wood stems and mature roots of plants called lenticels
What is Cohesion?
The attraction of water molecules to other water molecules
Why does water demonstrate Cohesion?
Because water is polar. It is slightly positive and slightly negative so it attracts other molecules of water
What is adhesion?
The attraction of water molecules to other molecules of a substance
How is root pressure created?
- Dissolved minerals are present in the cell due to active transport
- This creates a hypertonic concentration inside the cell
- The hypertonic solution draws in water by osmosis
- The water creates positive pressure which forces the fluid up the xylem into the low-pressure leaves
What does root pressure do?
Root pressure moves water from the roots of the plant to the leaves of the plant
What is the maximum root pressure can move water?
A maximum of only a few meters
What is the overall water movement process affected by?
Transpiration
Where does transpiration occur?
At the stomata
How does transpiration affect the plant?
As water is lost in the stem and leaves it must be replaced, and so water is drawn from the roots to the pant
Why are only certain cells dyed when a plant is placed in colored water?
Because water only flows through the xylem cells
How do substances have to be to be transported in plants?
They have to be dissolved in a film of water
What are the differences in pressure caused by in a plant?
Osmosis and Transpiration
How are minerals absorbed into plants?
By the root hairs by active transport
How does water enter the roots of a plant?
Through osmosis
What does the osmosis of water into the xylem tissue create?
Root pressure
What does root pressure do?
It forces water through the cells along the cell wall into the xylem
What is transpiration?
The evaporation of water through the stomata and lentils
What does transpiration create?
Tension or Transpiration pull
How does Tension or Transpiration pull work?
As water molecules evaporate it creates a pull on the other water molecules
-Then combined with the forces of cohesion and adhesion, the pull is enough to draw water up the xylem and into the leaf
What happens once the water is drawn up the xylem and into the leaf?
The water moves into the ground tissue
How does transpiration depend on temperature?
-If the temperature is high the rate of evaporation through the stomata will be high and the water movement in the xylem will be rapid
How high can water rise per a minute?
75 cm
What is the remaining water in the leaf used for?
It is used to manufacture sugars through photosynthesis and then the sugar is moved into the phloem
What is Tonicity?
The concentration of solute particles in a solution
What effect do changes in tonicity have on a plant?
They affect osmosis and the arrangement of structures in plant cells
What is plasmolysis?
The shrinking of the cytoplasm and membrane away from the cell wall due to outflow of water to a hypertonic environment
What is the outward effect of plasmolysis?
The leaf appears wilted or limp
What causes plasmolysis?
When water moves out of the cell in a hypertonic environment
What happens if a plant in a hypertonic solution is returned to fresh water?
The cells draw in more water end the cell is said to become turgid and cannot let any more water flow in
Why is turgidity important in plants?
It is important because it holds the green parts up toward sunlight
What is a critical process for plants?
Phloem transport
What are some ways phloem can be killed?
- Dehydration
- Excessive heat
What does phloem do?
It takes the products of photosynthesis from the leaves to the place where they will be stores, the sink
What is the sink?
The place where the products of photosythesis can be stored
What do sieve tube cells depend on?
Companion cells
What tissues are made out of sieve tubes?
Phloem
What do sieve tube cells depend on companion cells to do?
The movement of sugars into and out of sieve tube cells
How does the phloem become loaded with sugar molecules?
The companion cells use carrier proteins and active transport
How are glucose molecules moved into the plant?
Pressure Flow Theory
- When glucose enters the plant water molecules also enter the plant through osmosis
- The increased pressure inside the cells pushes water and sugar through the phloem to the rest of the plant and up at a sink
What are some forms of a sink?
Root
Tuber
Fruit
How do sugars reach other cells from the sieve tube cells?
The actively transported across cell membranes
What are the sugar molecules used for?
Growth, respiration, and other life processes
What happens as water leaves the sieve cells?
More water and sugar is pushed in the cells
What maintains a constant flow of food down the sieve tube?
The pressure differences produced by active transport and osmosis
What are stimuli?
A change in the environment that results in a reaction from an organism
What is phototropism?
When plants grow toward the light
What type of phototropism do stems exhibit?
Positive phototropism
What type of Phototropism do roots exhibit?
Weak negative phototropism because they grow away from the light
What is gravitropism?
Plant growth in response to gravity
What type of gravitropism do stems exhibit?
Negative gravitropism because they grow against the force of gravity
What type of gravitropism do roots exhibit?
Positive gravitropism
What is another name for gravitropism?
Geotropism
What do tropisms do?
Ensure survival of a plant
Which scientists conducted experiments about phototropism?
- Charles Darwin
- Peter Boysen-Jensen
- F.W. Went
What plant did the scientists who studied phototropism study?
The oat plant
What covers developing leaves?
An outer sheath
How high does the sheath grow in an oat or grass?
4-6 cm
What happens to a plant if the light only comes in one direction?
The sheath will bend towards the light source
Which part of the plant is responsible for the detection of stimulus?
The tip of the stem
What is the photoropic response created by?
The elongation of sheath cells
What is auxin?
The hormone produced in the tip of the plant responsible for the reaction of phototropism
How do plants know which way gravity is?
Plants rely on starch molecules in specialized cel
