Biology - Chp. 3 Multicellular Organisms

Question 1

What do specialized cells form?

Answer 1

Tissues and organs

Question 2

What do multicellular organisms use interal transport systems for

Answer 2

Efficient exchange of materials

Question 3

What are the Levels of Organization in Multicellular Organisms

Answer 3

Organism, Organ System, Organ, Tissue, Cell

Question 4

What are the 2 organ systems for plants

Answer 4

Shoot system - Everything above ground
Root System - Everything below ground (except tubers, Includes aerial roots)

Question 5

What are the three main types of tissues

Answer 5

Vascular Tissue (Xylem, Phloem)
Ground Tissue
Dermal Tissue

Question 6

What are the functions of Dermal Tissue (Epidermis)

Answer 6

• Outer Layer that covers all herbaceous (non-woody) plants
• Shoot system - responsible for the exchange fo oxygen and carbon dioxide
• Leaves and stems - Secrete waxy substance to form cuticle, protects plant from microorganisms from water loss
• Root system - uptake of water and minerals from soil (root hairs increase surface area)

Question 7

What are the Functions of the Ground Tissue

Answer 7

Stem - provides strength and support to the plant
Roots - involved in food and water storage
Leaves - Where photosynthesis occurs

Question 8

What are the functions of the Vascular Tissue

Answer 8

Xylem
- moves water and minerals from roots to shoots
- Composed of hollow, dead cells that dus together with perforation in the walls between the cells

Phloem Tissue
- transports dissolved sugars from shoots to roots
- vessels are formed from individual sieve tube cells with perforated end walls
- Sieve tube cells are alive but lose their maturity at. They are connected and controlled bu nucleated companion that controls movement
- Transported sugars are used for various cellular processes, converted into cellulose for plant structure, or stored as starch

Question 9

How does photosynthesis work

Answer 9

• takes place in the chloroplast (contains pigment chlorophyll that absorbs light energy from the sun)
• Plants make sugar (and oxygen as a waste product) with water and CO2

Question 10

How does cellular respiration work

Answer 10

• Glucose is used to produce ATP to be used as energy
• Glucose and oxygen creates water, CO2 and ATP
• During day, CO2 is taken in and O2 is released , the opposite is true at night

Question 11

What is the structure and function of the dermal tissue in leaves, stomata, guard cells and woody plants

Answer 11

Leaf
- clear, one or two cells thick to allow light to enter

Stomata
- tiny openings in the leaf (found in lower epidermis) allows for diffusion of CO2 and O2 and transpiration

Guard Cells
- regulate opening and closing of stomata
- Light hitting leaf causes guard cells to accumulate potassium ions through active transport. This results in water entering the guard cells through osmosis (increases turgor pressure)
- When turgor pressure is high, guard cells change shape and stomata open, allows for gas exchange and transpiration
- When pressure is low, guard cells change shape and stomate close and prevent water loss

Woody Plants
- epidermis is replaced by bark/cork
- gas exchange and transpiration occur in the lenticels (pores) along the stem

Question 12

What different tissues make up dermal tissue and what are there uses

Answer 12

• Palisade tissue cells are tightly packed and contain chloroplasts for photosynthesis
• Mesophyll tissue is spongy and loosely packed to allow for space for gasses to diffuse through the leaf (also contains some chloroplasts)

Question 13

What is the structure and function of vascular tissue

Answer 13

• Xylem and phloem are arranged in vascular bundles that extend throughout the plant and branch into finer veins within the mesophyll
• Xylem carries water and dissolved minerals from the roots to the rest pf the plant
• Phloem carries dissolved sugars from photosynthesis from the leaves to the rest of the plant

Question 14

What are the different methods for water transport in plants

Answer 14

Root pressure pushes - root cells bring minerals into the xylem (using active transport), which results in water flowing by osmosis (root pressure is the turgor pressure inside the xylem that pushes fluid upwards)

Transpiration Pulls - transpiration from leaves creates tension that pulls water up in an unbroken column. As water evaporates, more in pulled up to replace it

Cohesion - water molecules stick together (cause they’re polar) and creates an upwards pull of water from roots to leaves

Adhesion - Water molecules stick to certain surfaces, and prevents xylem sap from falling down to the roots

Question 15

What happens if a plant cell is placed in a hypertonic solution

Answer 15

Water will flow out of the cell and into the solution. This will result in the contents of the cell shrivelling and moving away from the cell wall and wilting

Question 16

What happens if a plant cell is placed in a hypotonic solution

Answer 16

Water will flow into the cell. The cell becomes turgid and stands upright

Question 17

How is sugar transported in a plant

Answer 17

• Products of photosynthesis flow from the leaves into the phloem
• The increase in solute results in osmosis bringing in more water into the phloem
• The water and sugars create more downwards pressure in the phloem
• The nutrients are slowly taken by other parts of the plant (roots, shoot, fruits etc.) are reduce the solute concentration.
• The reduced concentration allows for water to leave through osmosis
• This results in decreased pressure in the roots compared to the leaves and a consistent downwards flow

Question 18

What are the plant control systems or tropisms

Answer 18

Gravitropism - growth in response to gravity
- due to setting of starch in the plant
- Stems have negative gravitropism (they grow against the force of gravity)
- roots have positive gravitropism ( they grow towards the force of gravity)

Phototropism - Growth in response to light
- cells facing away from light tend to elongate
- Positive tropism - plants grow towards a light source

Charles and Frances Darwin
- The tip of the stem is responsible for detection of light stimulus
- It communicates with the rest of the cells to bend towards the light

Peter Boyson-Jensen
- Discovered that the tip of the plant needed clear access to the rest of the stem in order to observe phototropism
- Likely a result of a chemical (hormone) moving from the tip to the area of elongation

Positive hydrotropism - roots grow towards water

Thygmotropism - Growth in response to touch (stems climbing around a stick)