1. What are some of the problems that early land plants had to overcome to successfully colonize the land? 2. What was the most critical factor for the transition from life in the seas to life on land? 3. What are the requirments of photosymtheic organsms? 4. Are mitochondria and chloroplasts symbionts? 5. What evidence is there that mitochrondria and chloroplasts might be symbionts? 6. What advantages did early eukaryotic cells gain from incorporating mitochondria and chloroplasts into their own cells? 7. What advantages did free-living bacterial cells (like mitochondria & chloroplasts) gain from living inside eukaryotic cells? 8. Where do the 2 final stages of aerobic respiration take place in relation to mitochondrial structure? 9. Which molecules & ions cross the mitochondrial membranes during these stages? 10. Which wavelengths (colors of light) does chlorophyll b absorb most strongly ? (refers to the image below) 11. What color are carotenoids and WHY ? 10 12) Besides the Earth’s crust, what is the largest reservoir of carbon on Earth? 13) How many gigatons of carbon is humanity adding to the atmosphere each year? 14) Describe the state of ‘entropy’ in the a) open system. 15) Describe the state of ‘entropy’ in the b) closed system. 16) At what temp. does this enzyme have the highest ‘rate of reaction’ & what is the value? 17) Is this an enzyme found in humans? Why or why not? Solution 1. Early land plants faced a number of challenges when they began to colonize terrestrial territories.In order for plants to invade land, they had to contend with several challenges in the terrestrial environment. One of the challenges to living on land is the acquisition and conservation of water. Once plants moved onto land, they faced the problem of desiccation, or drying out. Most plants, except those that live in moist habitats such as mosses, obtain all their water through their roots. They have a number of adaptations that help them to conserve the water that they take in. These include a waxy cuticle, a covering over the surface of stems and leaves that helps prevent water from either entering or leaving the plant. Plants also have stomata, which are specialized openings that help regulate water loss. When the plant loses too much water to the atmosphere, the cells of the stomata close the opening, thus greatly reducing water lost through evaporation. Stomata are found in leaves, and allow carbon dioxide to enter the plant for photosynthesis and oxygen produced by photosynthesis to leave the plant. Reproducing on land is another challenge that the ancestors of plants had to overcome. A major problem is the transfer of gametes from one individual to another without drying up in the process. The most primitive land plants haven\'t overcome this challenge, which is why these types of plants, such as the mosses, still live in moist areas. There sperm must swim to the egg so they require the presence of water in order to get gametes from one individual .

1. 1. What are some of the problems that early land plants had to overcome to successfully colonize
the land?
2. What was the most critical factor for the transition from life in the seas to life on land?
3. What are the requirments of photosymtheic organsms?
4. Are mitochondria and chloroplasts symbionts?
5. What evidence is there that mitochrondria and chloroplasts might be symbionts?
6. What advantages did early eukaryotic cells gain from incorporating mitochondria and
chloroplasts into their own cells?
7. What advantages did free-living bacterial cells (like mitochondria & chloroplasts) gain from
living inside eukaryotic cells?
8. Where do the 2 final stages of aerobic respiration take place in relation to mitochondrial
structure?
9. Which molecules & ions cross the mitochondrial membranes during these stages?
10. Which wavelengths (colors of light) does chlorophyll b absorb most strongly ? (refers to the
image below)
11. What color are carotenoids and WHY ?
10
12) Besides the Earth’s crust, what is the largest reservoir of carbon on Earth?
13) How many gigatons of carbon is humanity adding to the atmosphere each year?
14) Describe the state of ‘entropy’ in the a) open system.
15) Describe the state of ‘entropy’ in the b) closed system.
16) At what temp. does this enzyme have the highest ‘rate of reaction’ & what is the value?
17) Is this an enzyme found in humans? Why or why not?
Solution
1. Early land plants faced a number of challenges when they began to colonize terrestrial
territories.In order for plants to invade land, they had to contend with several challenges in the
terrestrial environment. One of the challenges to living on land is the acquisition and
conservation of water. Once plants moved onto land, they faced the problem of desiccation, or
drying out. Most plants, except those that live in moist habitats such as mosses, obtain all their
water through their roots. They have a number of adaptations that help them to conserve the
water that they take in. These include a waxy cuticle, a covering over the surface of stems and
leaves that helps prevent water from either entering or leaving the plant. Plants also have

2. stomata, which are specialized openings that help regulate water loss. When the plant loses too
much water to the atmosphere, the cells of the stomata close the opening, thus greatly reducing
water lost through evaporation. Stomata are found in leaves, and allow carbon dioxide to enter
the plant for photosynthesis and oxygen produced by photosynthesis to leave the plant.
Reproducing on land is another challenge that the ancestors of plants had to overcome. A major
problem is the transfer of gametes from one individual to another without drying up in the
process. The most primitive land plants haven't overcome this challenge, which is why these
types of plants, such as the mosses, still live in moist areas. There sperm must swim to the egg so
they require the presence of water in order to get gametes from one individual to another. More
advanced plants have mechanisms that allow the transfer of gametes without drying out
including insects, wind and birds.
Plants require many nutrients, including large amounts of nitrogen, phosphorus, and potassium.
Algae living in the ocean are constantly surrounded by water, so they are able to get the nutrients
they need directly from the water that surrounds them--the nutrients diffuse into the cells.
However, plants on land are no longer surrounded by a source of these nutrients. Some plants
still live in moist habitats, but most gain nutrients from the soil, through their roots. The early
plants formed a symbiotic relationship with fungi called mycorrhizal fungi which aided the plant
in absorbing minerals. This plant/fungal association is still found today in about 80 percent of
plant families examined. The name "mycorrhizae" means fungus root. Some species of fungi
invade and form a close association with plant roots. The fungi help the plants take up mineral
nutrients from the soil; in turn, the fungi obtain energy in the form of carbohydrates from the
plants.
As plants adapted to dry land and became independent from the constant presence of water in
damp habitats, new organs and structures developed.Early land plants did not grow more than a
few inches off the ground, competing for light on these low mats. By developing a shoot and
growing taller, individual plants captured more light. Because air offers substantially less support
than water, land plants incorporated more rigid molecules in their stems. However, for plants to
evolve larger forms, the evolution of vascular tissue for the distribution of water and solutes was
a prerequisite. The vascular system contains xylem and phloem tissues. Xylem conducts water
and minerals absorbed from the soil up to the shoot, while phloem transports food derived from
photosynthesis throughout the entire plant. A root system evolved to take up water and minerals
from the soil, and to anchor the increasingly taller shoot in the soil.