Question

Chapter 29

1. Describe how the sporophyte and gametophyte stages of a plant life cycle differ.

2. Explain why most bryophytes grow close to the ground.

3. Explain why seedless vascular plants are commonly found in damp habitats.

Chapter 30

1. Explain how climatic changes with the formation of the supercontinent Pangaea favored the spread of gymnosperms.

2. Explain why pollen grains were an important adaptation for successful reproduction.

Chapter 35

1. Explain this statement: “In contrast to most animals, which have a stageof embryonic growth, plants have regionsof embryonic growth.”

2. Explain the difference between primarygrowth and secondarygrowth in plants.

3. Describe the major differences between annual, biennial, and perennial plants.

Chapter 36

1. Explain the benefits andcosts of the broad external surface area of many leaves.

2. Explain this statement: “In plants, the upward movement of xylem sap (water and nutrients) is ultimately solar powered.”

3. Explain how crassulacean acid metabolism (CAM) is an important adaptation to reduce transpiration in arid environments.

Answer 1

29.

1. In sporophyte fertilization takes place, by the combination of sex cells(haploid), whereas gametophyte stage is the stage of spores , production of eggs and sperms through mitosis occur.

2. Bryophytes grow near to the ground, because the does not posses conducting tissues. Conducting tissues help in the transportation of nutrients and water to each and every part.

3. Seedless vascular plants are commonly found in damp habitat because they posses breakable gametophores, cannot survive in dry condition. The sperm contain flagella, so it can easily swim to fuse with gametangia.

30.

1. Dry climate favour the spread of gymnosperms, because they lack flagella.

2. Pollengrains posses the male gamaetophyte, they mate with ovum, helps in genetic diversity. Pollens are carried by insects, animals and wind, so they shoud be well adapted to the climate for succesfull reproduction(for example - sticky nature of pollen help them to stick in insects body).

35.

1. In plants, both the flowers and leaves show determinate (embroyonic) growth whereas stem and root shows indeterminate growth.

2. Primary growth in plants helps in increasing length, whereas secondary growth helps in increasing the width or thickness. Apical meristem helps in primary growth, whereas lateral meristem helps in secondary growth. Primary growth is also know as longitudinal axis growth, whereas secondary growth is known as radial growth.

3. Annual plants are type of plants which grow, mature and produce seeds in one growing season, whereas biennial plants takes two years to complete its life cycle. Perennial plants take more than two years to complete its life cycle.

36.

1. Plants with broad external surface area leaves have both advantages and disadvantage, benefit is that, it helps them in performing photosynthesis, and produce more energy. Disadvantage is, loss of water from the leaves surface.

2. Xylem helps in the movement of water and nutrients from root to all parts of plants, this movement is against gravity, which is done by transpiration cohesion tension. Water from the leaves gets evaporated due to the heat, helps xylem to transport  water and nutrients in upward direction.

3. It helps the plants to reduce the water loss, by closing the stomata at day time and opening it in the day time.