lecture 6

Question 1

when a cell is flacid, the guard cells become

Answer 1

become less bowed and the pore closes

Question 2

when a cell is turgid, the guard cells..

Answer 2

bow outward and the pore between them opens

Question 3

what is a sugar source

Answer 3

an organ that is a producer of sugar, such as mature leaves

Question 4

what is a sugar sink?

Answer 4

an organ that is a consumer or storer of sugar, such as a tuber or bulb

Question 5

sugars are transported from sources to sinks via the:

Answer 5

phloem

Question 6

in many plants, phloem loading requires:

Answer 6

active transport

Question 7

what are the classifications of soil particles

Answer 7

sand, silt, clay

Question 8

what does topsoil consist of?

Answer 8

mineral particles, living organisms, and humus

Question 9

what is humus?

Answer 9

decaying organic material

Question 10

what are loams?

Answer 10

the most fertile topsoils, consisting of equal parts sand, silt and clay

Question 11

what are some examples of cations in soil?

Answer 11

K+, Ca2+, Mg2+

Question 12

cation exchange is stimulated by the:

Answer 12

roots

Question 13

without soil management, why is agriculutre bad? (3)

Answer 13

1. depletes mineral content of soil
2. taxes water reserves
3. encourages erosion

Question 14

plants with C4 and CAMphotosynthetic pathways always need which micronutrient?

Answer 14

sodium

Question 15

micronutrients function as :

Answer 15

cofactors, nonprotein helpers in enzymatic reactions

Question 16

deficiency of a mobile nutrient usually affects:

Answer 16

older organs more than young ones.

Question 17

deficiency of a less mobile nutrient usually affects:

Answer 17

younger organs more than older ones

Question 18

what 3 deficiencies are most common

Answer 18

nitrogen, potaassium, phosphorous

Question 19

a plant with a magnesium deficiency will:

Answer 19

first show signs of chlorosis in its older leaves

Question 20

what is chlorosis?

Answer 20

yellowing of plant

Question 21

a plant with an iron deficiency will:

Answer 21

cause yellowing of young leaves before older leaves

Question 22

nitrogen deficiency in maize is evident by:

Answer 22

yellowing that starts at the tip and moves along the centre of older leaves. the centre is called the midrib

Question 23

phosphorous deficiency in maize plants is evident by:

Answer 23

reddish purple margins, in young leaves

Question 24

potassium deficiency in maize plants is evident by:

Answer 24

“firing” or drying along the tips and margins of older leaves.

Question 25

what is the layer of soil that closely surrounds the plants roots?

Answer 25

rhizosphere

Question 26

what are endophytes?

Answer 26

nonpathogenic bacteria that live between the cells of host plant tissues

Question 27

nitrogen can be limiting of:

Answer 27

DNA, proteins, some carbs

Question 28

what are mycorrhizae?

Answer 28

mutualistic associations of fungi and roots

Question 29

what does ectomycorrhizae do?

Answer 29

mycelium forms a dense sheath over surface of root

Question 30

where do hyphae form a network?

Answer 30

in the apoplast

Question 31

what happens in arbuscular mycorrhizae?

Answer 31

microscopic fungi hyphae extend into the root, penetrating cell wall but not plasma membrane

Question 32

what are arbuscules?

Answer 32

important sites of nutrient transfer

Question 33

what are 3 unusual adaptations of plants using other organisms

Answer 33

1. epiphytes
2. parasitic plants
3. carnivorous plants

Question 34

what is an epiphyte?

Answer 34

an epiphyte grows on another plant and obtains water and minerals from rain. examples include staghorn ferns, some mosses, orchid species

Question 35

what are parasitic plants?

Answer 35

they absorb sugars and minerals from their living host plant. some examples include mistletoe, rafflesia, indian pipe

Question 36

what are carnivorous plants?

Answer 36

they are photosynthetic but obtain nitrogen by killing and digesting mostly insects. examples include pitcher plants, sundews, and venous flytraps