Unit 5: Plants

How do plants **adapt** to their environment?

* **photosynthesis**: 6CO2 + H2O →light→ C6H12O6 + 6O2
* **protection** from herbivores: tough, prickly outer layer
* **absorption through roots:** water and nutrients
* **gas exchange** through **stomata** (small holes)
* **reproduction**: ensure gametes unite, germinate, and grow

What is the **chemical formula** for **photosynthesis?**

6CO2 + H2O →light→ C6H12O6 + 6O2

What are **stomata?**

Small pores in the outer layer for gas exchange

What are the **three types of plant tissue?**

* **dermal:** outer cell walls __protecting__ against water loss, herbivores, injury, etc; covered in a waxy cuticle
* __**epidermis**__ and __**periderm**__
* **vascular:** __transports__ water and nutrients, provides support
* __**xylem**__ (thick, dead at maturity, __hollow__), __**phloem**__ (thin, living at maturity, __sieve__)
* **ground:** cellular __growth__, stores carbohydrates
* __**parenchyma**__ (thin, living at maturity)
* __**collenchyma**__ (thick, living at maturity)
* __**sclerenchyma**__ (lignin in cell walls, dead at maturity)
* **meristematic:** growth and specializes into different cells

What is and does **dermal tissue** do?

* outer cell walls __**protecting**__ against water loss, herbivores, injury, etc
* covered in a waxy cuticle
* __**epidermis**__ and __**periderm**__

What does **vascular tissue** do?

* __**transports**__ water and nutrients, provides support
* **xylem**: thick, dead, unidirectional __hollow__ (water and dissolved minerals)
* **phloem**: thin, living, multidirectional, __sieve__ (sugars from sources to sinks \[high → low conc’n\])

What does **ground tissue** do?

* cellular __**growth**__ and stores carbohydrates
* **parenchyma**: thin, living at maturity
* **collenchyma**: thick, living at maturity
* **sclerenchyma**: lignin in cell walls, dead at maturity

What does the **vascular cambium** do?

meristematic region that **forms new xylem** **and** **phloem** cells

What does **meristematic tissue** do?

Constantly dividing spells that eventually specialize into specifc tissues and growth

What are the **external** main **parts** of a **leaf?**

* **blade:** flat part of leaf
* **petiole:** the stem/stalk attached to the blade
* **veins:** holds the vascular tissue together (made of xylem and phloem)
* **venation:** pattern of veins in a leaf (__monocot__ = parallel, __dicot__ = network)

What are the **internal** main **parts** of a **leaf?**

* thin, flat cells in a single layer for light to enter
* **mesophyll**: specialized for photosynthesis
* **palisade**: many long, tightly packed chloroplasts (__catches sunlight__ for photosynthesis)
* **spongy**: loose cells for __gas exchange__ between envitinment and mesophyll (has vascular tissue)

What are leaves supposed to do - **function**?

* __**upper epidermis**__**:** the main source for photosynthesis and gas exchange through __stomata__ (small pores in the epidermis)
* **photosynthesis**: uses CO2 and releases O2
* **cellular** **respiration**: uses __O2__ and releases CO2

What do **stems** do?

* **connect** vascular tissue of **roots to leaves** (water and other disoslved substances migration)
* **support leaves** and reproductive organs (more sunlgight = better pollination)
* **storage** of **water** and carbohydrates

What are the **two types of stems?**

* **herbaceous:** fleshy, no wood, yes photosynthesis, *green*
* **monocot**: vascular bundles throughout
* **dicot**: vascular bundles in a ring
* **woody:** hard, yes wood/bark, no photosynthesis (many layers of xylem)

What is the **structure** for **woody stems?**

* **sapwood:** youngest xylem layer for water and mineral transportation
* **heartwood:** a bunch of __old sapwood__ layers together
* **cork:** outer layer, prevents water loss
* **cork cambium:** meristematic tissue between cambium and cork

What is **transpiration?**

Evaporation of water through stomata, absorbs water through root system

How does **water and minerals** transport through the plant?

* **active transport**
* **osmosis:** water enters through root epidermis into xylem vessel (high → low concentration)
* becomes **xylem sap** (liquid water/nutrients) upon entering vascular tissue
* build up of __xylem sap__ leads to more concentration and **root pressure** (pushes xylem sap up with help of *capillary action*)

What is a **source?**

Plant cell with high concentration of sugars and solutes (leaf)

What is a **sink?**

Plant with low concentration of sugars

How is **sugar transported** throughout the plant?

* **active transport:** source to phloem (low → high sugar concentration)


* **Translocation** (long distance sap movement)
* **passive transport:** phloem to sink (high → low sugar concentration)