Botany science olympiad 2026 div b

The functions of the roots

To anchor the plant, absorb water and minerals, transport nutrients, store carbohydrates, and signal and produce hormones.

The advantages of roots having a cylindrical shape

They can absorb nutrients from the entire circumference and are more effective at penetrating the soil.

Taproot System

Many smaller roots developed from a larger root called the radicle/embryonic root. They get more access to deep water, have deeper anchorage, and more storage.

Fiborous root system

Many similarly sized roots that exploit surface rainfall and have extensive shallow absorption. Commonly formed by adventitous roots.

Adventitous roots

Roots that come from abnormal places such as stems, nodes, and leaves.

The anatomy of a growing root tip in order of most mature to least mature.

Root Cap, Zone of cell division, zone of elongation, zone of differentiation/ maturation and root hair, Mature roots and lateral roots.

Root Cap

It secrets mucigel to reduce friction in order to protect the root apical meristem. And has gravity sensing. Cells are constantly being lost and replenished.

Gravity sensing

Root cap cells have dense starch filled structures that help the plant detect the direction of gravity.

Positive Gravitropism

Growing towards the direction of gravity

The zone of cell division

Directly behind the root cap, and where cells are constantly dividing through mitosis, where the root apical meristem is located, and where meristems become recognizable.

Protoderm

Develops into the epidermis

Ground meristem

develops into cortex/ground tissue

Procambium

Develops into the primary phloem and primary xylem

Root Apical Meristem

Contains actively dividing cells that contribute to the root cap, epidermis, cortex, and vascular tissues.

Zone of Elongation

Behind the zone of cell division, where cells rapidly absorb water, elongate, and enlarge, this pushes the root tip further through the soil. Which is the main contributor to root length.

Zone of differentiation/maturation

Behind the zone of elongation, cells mature and aquire their roles in the root. This is also where many root hairs are located.

In the zone of differentiation, epidermal cells _______

develop root hairs

In the zone of differentiation, xylem and phloem cells _______

Differentiate

In the zone of differentiation, the cotex _______

matures

In the zone of differentiation, the endodermis _______

develops

What differentiates or develops in the zone of differentiation

Epidermal cells form root hars, cortex matures, xylem and phloem differentiates, and endodermis develops.

Root hairs

Lateral extensions of a single epidermal cell that greatly increase the area of absorption. They’re short lived due to the roots movement through the soil.

The structure of a root from outermost to innermost

Epidermis, Cortex, Endodermis, Vascular cylinder

Root Epidermis

The outermost layer of a root, that is used for absorption and directly interacts with the soil. Root hairs come from these cell and unlike an ariel epidermis, they don’t have a cuticle.

_______ vascular tissues are make up most Herbaceous plants

Primary xylem and primary phloem

_______ tissues are make up most Woody plants

Primary xylem, secondary xylem, primary phloem, and secondary phloem.

Herbaceous plants increase in length, but woody plant increase in length and ______

Diameter

The main meristem for length in herbaceous and woody plants

Apical meristem (length)

The two lateral meristems in woody plants

The vascular cambium and cork cambium.

Lateral meristems in herbaceous plants

usually absent or inactive

In woody plants, ______ plant tissue is wood

secondary xylem

The protective outer tissue of herbaceous plants

Epidermis

The protective outer tissue of woody plants

An epidermis that matures into a periderm/bark

Grasses and wildflowers

Types of herbaceous plants

Trees, shrubs, and woody vines

Types of woody plants.

Primary growth is performed by

Apical meristem (Primary growth)

Shoots tips, root tips, leaves, flowers, and fruit

Parts of a woody plant that are mainly composed of primary tissues. Some older parts may grow more woody as secondary growth begins.

Increased length, Epidermis, Cortex, Pith, Primary Xylem, and Primary Phloem

Products of primary growth

Increased Diameter, Secondary Xylem, Secondary Phloem, Cork, and Periderm

Products of secondary growth

Structure of a young root tip

epidermis, cortex, primary phloem, provascular tissue, primary xylem, and the pith

Structure of an one year old root

Remnants of the epidermis and cortex, periderm, cork cambium, primary phloem, secondary phloem, the vascular cambium, secondary xylem, primary xylem, and the pith.

What happens to the epidermis and cortex in a woody plant over time

They are replaced by the periderm and cork cambium, and they begin to wear away.

What happens when the provascular tissue matures

It develops into the vascular cambium.

Structure of a three year old root

The periderm, cork cambium, primary phloem, secondary phloem, the vascular cambium, secondary xylem, primary xylem, and the pith.

The vascular cambium

A lateral meristem found in woody plants, that has a cylindrical shape. It is key for wood formation and is found between the secondary phloem and secondary xylem. It produces much more secondary xylem than phloem.

Tissues that make up the bark of woody plants

Secondary phloem, primary phloem, cork cambium, and periderm

Tissues that make up wood

Only the secondary xylem

Fusiform initials

Produces Long, narrow cells to make the ariel xylem and phloem. The cells that they produce are used for vertical transport and support.

Ray initials

Produces shorter cells for the secondary xylem and phloem rays, that provide lateral transport and storage.

Axial system

Systems that run up and down the stem. Some examples of this are xylem vessels, and phloem sieve tubes.

Radial system

A system that runs sideways through the stem, mainly using rays.

Rays in woody plants

Lateral structures that run across the stem. They are either secondary xylem or secondary phloem rays based on their structure and roles. They’re a part of secondary growth and originate from the vascular cambium.

The _________ develops from the vascular cambium, and is made up of trachieds, vessel elements, xylem fibers, and parenchyma cells. And they compose wood

Secondary xylem

The wood in gymnosperms is called _______ and is mainly composed of trachieds. They provide water transportation and support, They lack large vessel elements, making the wood very uniform.

Softwood

The wood in angiosperms that contains vessel elements for water transport and xylem fibers for strength. This makes the woods structure complex and diverse.

Hardwood

Vessel elements

In the xylem, they provide quick water transport, specifically in angiosperms. They are composed of a single cell

Tracheids

In the xylem they offer water trasnport and storage. They are composed of a single cell

Fiber cell

Used for strength and mechanical support. They are composed of a single cell

Xylem Parenchyma

Mainly used for storage and they are composed of a single cell

They are used for lateral transport and storage. They are composed of a single cell

Ray parenchyma

Where the primary xylem originates from

It comes from the procambium which originates from the apical meristem. It forms during primary growth/ lengthening

Where the secondary xylem produced from

It is produced by the vascular cambium, and comes during secondary growth.

How the primary xylem is arranged

a system of vascular bundles

How the primary xylem is arranged

In layers of wood, rays, and rings

Annual ring appearences

Rings created by the xylem have visibly different appearances at different times of the growing season

Earlywood/ Springwood

Produced during the rapid growth period at the beginning of the growing season. The cells have larger diameters, thinner walls, and efficient water transport.

Latewood/ Summerwood

Produced later in the growing season when growth is much slower. The cells are smaller but have larger walls and are mainly used for mechanical support.

How annual rings are formed

The visible transition for latewood to the earlywood of next growing season

How growth rings can indicate climate and enviormental conditions

Smaller rings indicate less favorable conditions

Ring-porous

Wood that contains large earlywood vessels that clearly mark the difference between early and latewood.

Semi-ring-porous

A gradual transition between early and latewood vessels.

Diffuse-porous

The transition between early and latewood has no visible difference, because there is a much smaller difference in diameter between early and latewood vessels.

Sapwood

The younger, outer secondary xylem that has living parenchyma, stored nutrients, its main function, transport of water and minerals.

Heartwood

The older, inner secondary xylem that can no longer transport water, and the majority of its parenchyma are dead. Its main function is mechanical support.

Which tissues are part of bark

Everything inside of the vascular cambium such as the secondary phloem, primary phloem, cork cambium, and the periderm.

How the phloem accumulates in woody plants

The younger secondary phloem crushes the primary phloem so only the inner phloem can remain actively transporting sugars. They remain active for much less time then xylem.

What happens to xylem as it accumulates in woody plants

They are active for much longer than phloem, before becoming heartwood.

Formation of the periderm

As the stem increases in diameter the cork cambium develops and produce cork. Then the tissues combine.

Periderm

Replaces the epidermis and cortex in woody plants. Made up of cork and the cork cambium.

Cork

Protective and effective at reducing water loss. formed by the cork cambium and makes up most of the periderm.

Lenticels

Openings in the periderm, in woody plants that allow for gas exchange in the stem.

Woody Monocots

They don’t have lateral meristems or secondary growth. Instead they have not true wood the is made up of hardened fibers and pliable tissues.

Angiosperm sexual reproduction

More diverse because of combining different genes, but because they are different they cannot colonize new locations as quickly. Some can spread to places where parents can’t go and they are more resistant to diseases. They can’t reproduce alone.

Asexual reproduction

They are all identical and can quickly colonize but lack diversity and are heavily affected by disease and changes. They can reproduce alone.

Life cycle of an Angiosperm

Flower grows, gametophytes, pollination, double fertilization, seeds and fruits, dispersal, and germination.

Gametes

Sperm cells or egg cells

The flower

The reproductive shoot of an angiosperm

Sepal

The outermost leaf like structure that protects the young flower bud.

Petals

Colored leaf like parts inside of the sepal that attract pollinators with bright colors and smells.

Stamen

Male reproductive organ of angiosperms that includes the filament and anther.

Filament

Part of the stamen, and holds up the anther.

Anther

Part of the stamen, and produces pollen

Carpel/ Pistil

Female reproductive organ of angiosperms that includes the stigma, style, ovary, and ovules.

Stigma

Part of the carpel, and receives pollen

Style

Part of the carpel, and is where the pollen tube grows through.

Ovary

Part of the carpel, and contains the ovules

Ovules

Part of the carpel, contains the female gametophyte, and becomes seeds

Complete flower

A flower with all sepals, petals, stamens, and carpels.

Incomplete

I flower missing at least one of the major floral organs

Perfect Flower

A flower with a stamen and carpel