Lesson 4 RQ/Quiz
Match the names with the correct parts of the root.(cross-section of a root) - Which part is the cortex? - Which part is the endodermis? - Which part is the phloem
- d - c - e
State what each of these plant hormones do. auxins cytokinins gibberellins abscisic acid ethylene
Auxins: plant hormones that influence cell elongation, gravitropism, apical dominance, and root growth Cytokinins: plant hormones that promote cell division Gibberellins: plant hormones that stimulate shoot elongation, seed germination, and the maturation and dropping of fruit and flowers Abscisic acid: plant hormones that induce dormancy in seeds and the plants' other organs Ethylene: plant hormones that are associated with the ripening of fruit, wilting of flowers, and the falling of leaves.
What is the structure and function for dermal, vascular, and ground tissues?
Dermal tissue covers the plant as protection and is a simple tissue that covers the outer surface of the plant and controls gas exchange. Vascular tissue transports water, minerals, and sugars to different areas of the plant and it is a complex tissue. It is made of xylem and phloem. Xylem tissue transports water and nutrients from the roots and phloem tissue transports organic compounds from the place of photosynthesis to other areas of the plant. Ground tissue is a site for photosynthesis and provides a supporting matrix for the vascular tissue. It also stores water and sugars
Discuss gravitropism, thigmotropism, and phototropism.
Gravitropism is growth of a plant in response to gravity and directs root growth toward the pull of gravity and stem growth in the opposite direction. Thigmotropism is plant growth in response to touch or contact with a solid object. Climbing plants or vines demonstrate thigmotropism. An example of thigmotropism is plants growing and intertwining all around a metal fence. Phototropism is the directional growth of organisms in response to light and growth towards it. Plant cells have photoreceptors that detect light where they make the plant attracted to the light and grow towards it.
On a piece of paper, draw a stem and label the nodes, internode, axillary bud, petiole, and apical bud. Did you finish your drawing? Define each label here.
Nodes: nodes are points on the stem where leaves or flowers grow out Internode: the internode is the stem that is in between two nodes Axillary bud: an axillary bud is where a branch or flower might grow out at the area between the base of a leaf and the stem. Petiole: the petiole is the stalk that connects the leaf to the stem. Apical bud: A bud that is formed at the tip of the stem shoot.
Explain the differences between primary growth and secondary growth in stems.
Primary growth is growth resulting in an increase in the length of the stem and the root which is caused by cell division in the shoot or root, while secondary growth is growth resulting in an increase in thickness and is caused by the lateral meristem and cork cambium.
Compare primary and secondary growth.
Primary growth usually occurs at the tips of stems and roots and increases the length of the stem. Secondary growth is the growth that occurs by the action of the cambium that increases the diameter of the plant.
Describe how red and blue light affect plant growth and metabolic activities.
Red light converts the photoreceptor phytochrome in plants to its far-red light-absorbing form that controls germination and flowering in response to the length of the day, as well as triggers photosynthesis in dormant plants or those emerging from the soil. Blue-light receptors are responsible for phototropism and amyloplasts in plants sense gravity which regulates the opening of the stomata and helps with photosynthesis if at low levels.
What does "source to sink" mean?
Source to sink refers to translocation which is the mass transport of photosynthates in vascular plants. Structures that produce photosynthates for a growing plant are called sources while sinks are the points of sugar delivery such as roots, shoots, or developing seeds.
What is a stem modification? Give an example.
Stem modifications are ones that are suited for a particular environment. For example, rhizomes grow horizontally underground and have nodes and internodes. Some shoots may grow from the buds of the rhizome on some plants such as ginger and ferns.
Describe the main function and basic structure of stems.
Stems are characterized by nodes and internodes. Nodes are the points of attachment for the leaves or flowers. The stem between two nodes is an internode. A petiole is a stalk that extends from the node to the base of the leaf Stems also have dermal tissue, ground tissue, and vascular tissue that support the stem.
Describe the internal structure and function of a leaf.
The epidermis is the outer layer of the leaf and protects the leaf from additional water loss from transpiration. What covers leaves is a waxy layer called the cuticle that also reduces the rate of water loss from the leaf's surface. In between the upper epidermis and lower epidermis is the mesophyll, which has the palisade parenchyma and the spongy parenchyma. The palisade parenchyma has column-shaped and tightly packed cells that contain the chloroplasts in the leaves. The spongy parenchyma is loosely arranged cells in an irregular shape. The air between the spongy and palisade parenchyma allows gaseous exchange between the leaf and the outside atmosphere through the stomata. Guard cells are on the outside of the cuticle and epidermis. They regulate the rate of transpiration by opening and closing the stomata.
How do plants defend themselves from diseases and organisms that want to eat them? Give specific examples.
The first level of defense against herbivores and pathogens is bark and plants' waxy cuticle. Other ways plants defend themselves against herbivores include thorns that cause physical damage to the predators such as rashes and allergic reactions.
Describe the structure of a root and root modifications.
The outer layer of a root has cells called the epidermis, that surround areas of ground tissue and vascular tissue. It provides protection and helps in absorption; root hairs are extensions of root epidermal cells and increase the surface area of the root while helping in the absorption of water and minerals. Inside the root is ground tissue that makes the cortex and the pith which store photosynthetic products. The cortex is between the epidermic and the vascular tissue while the pith is between the vascular tissue and the center of the root. Root modifications are structures that may be modified for specific purposes. For example, carrots, turnips, and beets are roots that are modified for food storage.
What are the functions of parenchyma cells, collenchyma cells, and sclerenchyma cells?
The parenchyma cells are found in the stem, the root, the inside of the leaf, and the pulp of the fruit. They are responsible for metabolic functions like photosynthesis and help repair and heal wounds. Collenchyma cells are elongated and have unevenly thick walls. They serve as additional support and in the growing parts of the plant such as shoots and leaves. They fill in vacant spaces that are used later for growth. Sclerenchyma cells provide support to the plant but are dead at maturity. They are found in nongrowing areas of the plant such as the bark or fully grown stems.
On a piece of paper, draw the parts of a typical leaf and label them. Did you finish the diagram? Briefly state the functions of each of the labeled parts.
The parts of a leaf include the tip, midrib, margin, vein, petiole, and lamina. Tip: the tip of the leaf. Midrib: travels the length of the leaf and branches that produce veins. Margin: the edge of the leaf Vein: the vascular tissue pattern on the leaf Petiole: the stalk of the leaf providing support Lamina: the leaf blade
On a piece of paper, draw a root and label the parts. Did you finish the diagram? Briefly state the functions of each of the labeled parts.
The parts of the root include the lateral root, primary root, root hairs, the root tip, and the root cap. Lateral root: The roots that stem out of the primary root. Primary root: The main root where other roots stem out of. Root hairs: extensions of root epidermal cells and increase the surface area of the root while helping in the absorption of water and minerals Root tip: Bottom tip of the root and helps with the downward growth of the root. Root cap: how the tip of the root is protected
Which of the following statements is not true of plant vascular tissue?
Tracheids and vessel elements have different functions.
How is transpiration controlled?
Transpiration is controlled by a waxy layer called the cuticle that covers leaves and prevents the loss of water. Guard cells also control transpiration because they control the opening and closing of the stomata to release water.
Discuss transpiration in plants.
Transpiration is the loss of water vapor in plants to the atmosphere through the stomata. The process is passive which means that ATP is not required for the water movement.
Define water potential and explain how it is influenced by solutes, pressure, gravity, and the matric potential.
Water potential is the measure of potential energy in water. Solutes reduce water potential by consuming some of the potential energy in the water and is negative. Pressure potential may be positive or negative; the higher the pressure, the more potential energy in a system, and the same with vice versa. Gravity potential is always negative to 0 in a plant with no height. The force of gravity pulls water downwards to the soil which reduces the total amount of potential energy in the water of the plant. Matric potential is negative to zero and the binding of water to a matrix always removes or consumes potential energy from the system.
Which hormone helps the plant retain water by preventing transpiration?
abscisic acid
Which hormone has the greatest influence over leaf abscission?
auxins
Vessel elements are not
connected with pits.
Which of the following cell layers is not a meristematic region of cell growth in a plant?
cortex
Which hormone has the greatest influence over delaying senescence (aging) of leaves?
cytokinins
Hard green tomatoes can be picked and transported across the country and then cued to ripen on demand by using which hormone?
ethylene
Which of these plant cells is the one that most often divides?
meristem
Secondary growth
produces xylem and phloem
Which of the following concentric tree layers is incorrectly paired with the type of cell it is made of?
sapwood—living phloem
Tree bark consists of all of these except
secondary xylem
Which of these terms refers to the plant's response to touch?
thigmotropism
Write the equation for water potential and identify what each symbol represents. What units are used for water potential?
Ψsystem=Ψtotal=Ψs+Ψp+Ψg+Ψm Ψs, Ψp, Ψg, Ψm represent the solute, pressure, gravity, and matric potentials. Ψsystem refers to the water potential of the soil water, root water, stem water, leaf water, or the water in the atmosphere. Ψtotal refers to the total water potential. Water potential is denoted by the Greek letter psi and is expressed in units of pressure called megapascals.
