Seed-Producing Plants

Seed Producing Plant Written Answers

By Nikki

1. Distinguish between the following:

a. Sapwood and heartwood are both different densities that contribute to the pattern of the wood (annular rings). Heartwood is the innermost layer of the tree that are oldest parts of the tree. This is the part of the tree that is too clogged up with cellulose from the xylem and cannot properly transport water. The heartwood is the xylem on the outer layers of the tree that is not functioning any longer. Sapwood on the other hand is the part of the tree that still has functioning layers of xylem that can still transport water. The combination of the sapwood and the heartwood are different densities which creates the pattern and grain of the tree.

b. Seeds are embryonic, unlike spores, and are genetic packages capable of growing into organisms from their food source which is enclosed in the embryo. Spores on the other hand are produced by meiosis and are reproductive structures. They are adapted to be despersal delivery packages that are ready to survive for extended periods of time in harsh condtitions. Spores are the units of asexual reproduction, because a single spore develops into a new organism.

c. Needles in comparison to leaves are much better at absorbing water and can therefore live in dryer climates due to their smaller amount of surface area. Needles are basically an adaptation of leaves that have specialized them to be able to stay fully hydrated. Leaves on the other hand are very good at absorbing sugar (photosynthesis) because they can have a very large surface area unlike needles which are very small in surface area. Leaves also have a vascular system which are in the form of veins which makes transportation of water and nutrients throughout the plant much easier.

d. Male cones are much smaller than female cones and are located at the tip of the branches for easy wind access. Male cones are the cones that produce pollen grains (sperm) which are made to be transported by the wind in search of female cones. Female cones are much larger, and when mating season arrives are specialized to actually spread out their cone scales so that pollen can enter and fertilize the ovum. Once the pollen has fertilized the ovum,  the pollen tube nucleus controls the pollen tube and continues to elongate and help it grow.

2. How do the processes of osmosis and transpiration contribute to the movement of water in a plant system?

“Osmosis is the movement of water due to solate concentration gradients. Water will move to satisfy the Laws of Diffusion, which state that particle movement leads to equalizing of concentration differences.” That being said plants use the osmosis created by the transportation of mineral nutrients into the cells. The water then gets conducted to the vascular tissue with osmosis which continues to transport it towards higher concentrations of dissolved substances in the tissues of the root tips. Transpiration on the other hand, is the process of water molecules sticking together so when a water molecule evaporates another molecule while take it’s place. This action accounts for the water and nutrient movement up a stem.

3. Describe the function and location of the Caspian strip.

The Caspian strip is a waxy layer located in the stele of the pant which is the central part of the root or stem. It is a band of water-proof cell wall material that blocks the passive flow of materials. This waxy layer between the cells of the endodermis stops water and solutes from entering the xylem, unless they pass through the cytoplasm of adjacent cells.

4. What is “wood”? What types of cells is it made of and what kinds of plants develop wood?

Wood is the hard fibrous substance which composes the body of a tree and its branches and is referred to as a precious commodity in the sense that it is a renewable resource. Wood is made up of various types of cells specialized for each of woods purposes. Among them are tracheids which are called support cells, parenchyma (food storage), and xylem vessels, formed of hollow cells joined end to end. Parenchyma cells and xylem cells are made by a meristematic tissue called the vascular cambium. Wood is yielded by trees which are usually nowadays angiosperms which had originally evolved from gymnosperms (some of the earliest trees.)

5. Distinguish between monocots and dicots on the basis of the structure of seeds, flowers, stem, leaves, and roots.

Monocotyledon and Dicotyledon are the two main groups of flowering plants, which stand for monocots and dicots. Both subdivisions have strong characteristics which make it very clear to distinguish between the two.

-Monocots flower parts in multiples of threes, whereas Dicots flower parts in multiples of four or five.

-Monocots have vascular bundles that are scattered within the stem. Dicot’s on the other hand stems vascular bundles in a ring.

- Monocots roots are considered adventitious, while Dicot roots develop from radicle

- Monocots have leaves with their major veins running parallel with the length of the leaf. Dicot leaves have many auxiliary veins which reticulate between the major veins.

-  As the for the seeds of dicots and monocots, this remains one of the most visible and reliable hint in distinguishing between the two and originally gave them their names. Dicots usually have a slit going down the middle of their seed, which separates the seed into two large parts called cotyledons. Inside of the two parts usually lies an embryo that actually use the two cotyledons which enclose it as a food source. Monocot seeds on the other hand only have one cotyledon which encloses an embryo. Just outside the embryo protecting and supplying the embryo is called the endosperm, a thick usually lighter coloured part of the seed. One way of easily telling the difference between a monocot and a dicot is to see if the seed splits into two even pieces or not.