Chapter 37

Plants need a variety of things to live: Water and carbon dioxide Chemical elements Minerals Soil Nitrogen

Soil, air and water all contribute chemicals to plants

Plants extract mineral nutrients from the soil in the form of inorganic ions.

Water acts as a solvent; provides the majority of a cell’s volume; and keeps cells turgid

Organic materials include cellulose and sucrose

C, H, and O are the most abundant elements in plants

N, S, and P are the next most abundant

17 essential elements have been identified in plants.

9 are macronutrients because they are required in large amounts (C, O, H, N, P S, K, Ca, Mg)

The remaining 8 are micronutrients (Cl, Fe, Mn, B, Zn, Cu, Ni, Mo)

If a plant doesn’t have the minerals it needs, it is deficient.

Symptoms include: Yellow leaves Decreased chlorophyll Red leaves Shriveled or wrinkled leaves

Topsoil is a mixture of particles derived from rocks, living organisms and humus (the remains of partially decayed organic materials)

Loam is the most fertile soil, made of sand and silt, and little amounts of clay

Soil is made of both organic components, minerals, and living organisms.

It takes many centuries of decomposition for soil to become fertile

Agriculture naturally depletes soil quality Crops must be rotated to restore minerals

Fertilizers usually contain N-P-K in a 15-10-5 ratio

Manure, compost, and dead fish are good fertilizers

Chemical fertilizers produce pollution, are not retained by the soil, and must be reapplied constantly

pH affects whether or not plants can absorb minerals and ions

Every plant has a different pH need, but most prefer soil that is neutral or slightly basic

80% of our atmosphere is N2, which plants can’t use Nitrogen fixing bacteria converts N2 to NH4

+ and NO3-

The most important bacteria is called Rhizobium bacteria, which lives in little swellings in plant roots called nodules

Epiphytes nourish themselves but grow on a another plant (ferns, orchids)

Parasitic plants absorb sugar and minerals from their living hosts (mistletoe)

Carnivorous Plants are photosynthetic but obtain nitrogen by killing and digesting insects (Venus flytrap, pitcher plants)

Chapter 38

Pollen from stamen travels down the pollen tube of the carpel and fertilizes an egg

Zygote (2n) forms, divides into embryo, forms fruit

Fruits have seeds (developed from ovules)

Seed is dispersed, germinates, makes a new plant

1. Pollen sacs (microsporangium) contain diploid microsporocytes

2. Each microsporocytes divides by meiosis to produce 4 haploid microspores, each develops into a pollen grain

3. A pollen grain matures when its nucleus divides in two and forms two sperm (this happens after it lands on the stigma)

4. Then it grows a pollen tube so the sperm can swim down to fertilize the egg

1. Within the ovule’s megasporangium is a large diploid megasporocyte

2. The megasporocyte divides by meiosis and makes 4 haploid cells, but only one survives to become and megaspore

3. The megaspore divides 3 times, to form the embryo sac, a multicellular female gametophyte. This is the ovule.

Some flowers, like garden peas, self-fertilize Most flowers prevent self-fertilization: Some have separate male and female

flowers Male and female parts might mature at

different times Plants can reject their own pollen

1. A pollen grain lands on the stigma, and grows a pollen tube down the style towards the ovary

2. The pollen tube squirts out two sperm

3. One sperm fertilizes the egg, forming the zygote.

4. The other sperm combines with 2 of the polar nuclei (the eggs that didn’t survive) to become the endosperm (the food for the seed)

The embryo goes through mitosis to form a seed.

A seed has a coat, an endosperm (food), cotyledons (baby leaves), shoots, and roots

While the seeds are developing from ovules, the ovary of the flower is developing into a fruit.

There are 3 fruit types: Simple: develop from a single

carpel of one flower (pea pod) Aggregate: develops from

many carpels of one flower (raspberries)

Multiple: develops from many carpels of many flowers (pineapple)

Seeds can remain dormant until conditions are right for germination

Germination starts with water uptake called imbibition.

The first organ to emerge is the root (from the radicle)

Next the shoot breaks through the soil surface

Plants can clone themselves through asexual reproduction

Fragmentation is the separation of a parent plant into parts that develop into new plants

Dandelions can produce seeds without pollination (apomixis)

You can make clones from plant cuttings in your house

Grafting is attaching the stem of one plant to the roots of another