Section 3 Flashcards
How do single-celled organisms carry out all life processes? What happens if it gets too large?
They maintain an efficient surface area to volume ratio. If a cell becomes to large, it will usually divide to produce two new cells.
What are 3 advantages of multicellular organisms? Explain your points.
1) Division of labour; cells perform their specialized purposes more efficiently than a single-celled organism that would have to perform all needed functions at once.
2) Size; in multicellular organisms, internal transport systems allow efficient exchange of materials, letting the organism grow to a larger size.
3) Interdependence of cells; life of a multicellular organism does not depend on a single cell.
What’s a disadvantage of a multicellular organism?
Cells cannot survive alone as they depend on others for certain tasks.
What is a tissue?
A group of similar cells performing the same function.
What is an organ?
Tissues contributing to the same function in a structured and functional unit.
What is an organ system?
A group of organs working together for a specialized task.
What is the shoot system? Name the organs apart of it.
The shoot system is generally everything that is above ground; includes stem, leaves, buds, flower, fruits. It also includes tubers even though they are underground.
What are tubers?
Swollen stems that store food (eg. potatoes).
What is the root system? Name the organs apart of it.
It’s generally everything underground, like the roots.
What are meristems?
These are sites of rapid cell division. These areas are found a the end of growing leaves and roots and is where growth and development occur. Different meristems produce root and shoot tissue.
How are the cells of a meristem different from a regular cell?
Meristems have less specialized cells and cell division occurs much faster
What is dermal tissue/epidermis? What is its role in leaves and stems? What about roots?
It’s a very thin outer layer of cells that covers all parts of herbaceous plants (in woody plants, it’s replaced by cork and bark). On leaves and stems, it’s main function is to facilitate gas exchange. In roots, it’s responsible for the uptake of water and mineral salts from the soil.
What is the cuticle?
Dermal cells create the cuticle that helps protect the plant from diseases and microorganisms, and prevent water loss.
What is the ground tissue? What’s it’s role in the stem? the roots? The leaves?
It’s beneath the epidermis and makes up majority of the plant.
Roles:
Stem: provides strength and support
Root: food and water storage
Leaf: site for photosynthesis (contains chloroplasts)
What is a herbaceous plant?
A non-woody plant.
True or False: the cells of ground tissue are tightly packed to allow gases to diffuse easily around the cells.
False; they are loosely packed.
What is the role of vascular tissue?
Transport of materials throughout the plant.
What does xylem tissue do?
It moves water and dissolved minerals from the roots up the stem to the leaves for photosynthesis
Explain how xylem vessels are formed.
Cells fuse together and end walls become perforated. The cytoplasm then breaks down and cells die, leaving the non-living cell walls attached like a long straw.
What does phloem tissue do? What can the substance it transports be converted into?
It transports the products of photosynthesis (dissolves sugars) from the leaves to the rest of the plant. It can be converted into cellulose or stored as starch in the roots/leaves.
What is phloem formed from?
Sieve tube cells.
Which is larger: xylem or phloem?
Xylem
What are sieve tube cells?
- Remain alive but lose their nuclei
- In many plants, they are controlled by companion cells
- Allow cytoplasm to stream between cells
- Pushes water and sugars through phloem
Cells no longer apart of the ___________ show the characteristics of only certain parts of their genetic code. They become _________________.
Meristems; specialized
What are root hairs responsible for?
They increase the surface area of the root to maximize the rate of water absorption into the plant.
True or false: the epidermis is responsible for creating the cuticle.
True
What are guard cells?
Specialized cells that swell and contract to allow gas exchange. They regulate stomata size. They are the only cells in the epidermis that contain chloroplasts.
What are stomata?
They are tiny pores on the underside of leaves that facilitate gas exchange. Found mainly on the lower epidermis.
Why are stomata found mainly on the lower epidermis?
Direct sunlight absorbed in upper epidermis would cause evaporation of water.
Humid areas: ___________ (more/less) stomata.
Dry areas: ___________ (more/less) stomata.
More; less
True or false: Cells apart of the xylem do not need to specialize to be able to conduct water.
False.
Is the leaf a tissue, organ, or system?
An organ.
The leaf’s main role is to?
Carry out photosynthesis.
What special organelle is responsible for photosynthesis? Where are they found?
The chloroplasts; they are found in the ground tissue of leaves and sometimes the stem.
What is the word equation for photosynthesis?
water + carbon dioxide —> (with light and chlorophyll) glucose + oxygen
Chloroplasts contain the green pigment called?
Chlorophyll
What does chlorophyll do? Where is it found?
- Reflects + transmits green light
- absorbs light energy
- stores it as chemical energy in glucose
- found in the thylakoids of the chloroplast (stacks of these are grana)
What are stacks of thylakoids called?
Grana
Does photosynthesis occur day and night?
NO; it needs light to function so it only works in the day.
What is cellular respiration used for?
It’s the process by which animals and plants convert the stored energy in their food (glucose) to usable energy.
Cellular respiration begins in the _____________ but ends in the _____________.
Cytoplasm; mitochondria
The movement of chloroplasts within cells has given indirect evidence of?
Cytoplasmic streaming