plant physiology-unit 3

Question 1

where is starch found in the leaf

Answer 1

in the parts of the plant that contain chlorophyll

Question 2

investigation for testing leaves for starch

Answer 2

-remove the waxy outer layer
-drops of iodine
-leaf boiled to stop all chemicals in the leaf from happening in tube containing ethanol
-boil to remove most of the chlorophyll in the leaf
-when colorless/pale, wash in cold water and place drops of iodine solution
-any part of the solution that contain starch will turn blue black.

Question 3

facts about starch production by leaves

Answer 3

-uses carbon dioxide from the air
-it needs light
-it needs chlorophyll from the leaves

Question 4

the process of photosynthesis

Answer 4

in the presence of chlorophyll and light, plants can make glucose and oxygen from co2 and water

-green pigment chlorophyll absorbs light energy needed for reaction to take place
-glucose and oxygen contain more energy then co2 and water, meaning it converts light energy into chemical energy

Question 5

balanced equation for photosynthesis

Answer 5

6co2 + 6H2O —-chlorophyll—-C6H1206 + 6O2

Question 6

structure of a leaf

Answer 6

-two outer layers(upper/lower epidermis)-covered by waxy layer (cuticle)
-lower epidermis=has many stomata-this allows C02 to diffuse into leaf, also allow water and oxygen to diffuse out
-(guard cells= open and close soma)
-middle of leaf is called mesophyll
-palisade mesophyll layer below upper epidermis contains lots of chloroplasts
-below palisade layer is spongy mesophyll. fewer chloroplast lots of air space, main gas exchange of the leaf(air spaces allow gases to diffuse in and out of mesophyll)
-xylem-vessel transfers water from roots to leaf vessel (water absorbed from roots into veins)
-phloem- vessel transfers glucose from plant(photosynthesis) to rest of plant

Question 7

limiting factors of photosynthesis

Answer 7

limiting factors=prevents rate of reaction from increasing

1. light intensity
   2.co2 concentration
2. temperature

Question 8

function of epidermis

Answer 8

waxy material= cuticle
-prevents water loss
-acts as barrier for bacteria

Question 9

function of lower epidermis

Answer 9

-has many stomata (holes)- allows co2 to diffuse into leaf and oxygen and water vapor to diffuse out
-each stoma is formed as a gap between two guard cells

Question 10

function of guard cells

Answer 10

change their shape to open or close the stoma

Question 11

function of palisade mesophyll

Answer 11

-tissue made of lots of chloroplast
-main site of photosynthesis
-close to light source
-relatively transparent

Question 12

function of spongy mesophyll

Answer 12

layer of tissue with fewer chloroplasts
-main gas exchange surface of the leaf
-absorbs Co2, releases oxygen and water vapor
-air spaces allow gas to diffuse in and out of mesophyll

Question 13

what does mesophyll mean

Answer 13

middle of leaf

Question 14

function of xylem

Answer 14

continuous transport of water absorbed my roots to the veins and supplies mesophyll

Question 15

functions of phloem

Answer 15

products of photosynthesis is carried away by phloem and supplies all other parts of plants

Question 16

practical for measuring rate of photosynthesis

Answer 16

-how quickly a plant can produce oxygen
-cut a piece of weed and leave in test tube
-change the light intensity by altering distance
-control other variables

Question 17

uses of mineral ions in plants

Answer 17

mineral ions like nitrate, phosphate, potassium and magnesium are absorbed from soil water

phosphate =making important compounds like DNA, part of cell membrane
nitrate= making amino acids, proteins, chlorophyll
potassium= needed for enzymes of respiration and photosynthesis to work
magnesium= parts of chlorophyll molecule

Question 18

deficiency symptoms of plants without mineral ions

Answer 18

nitrate= limited growth, old leaves turn yellow
phosphate= bad root growth, young leaves turn purple
potassium= turns leaves yellow, dead spots
magnesium= leaves turn yellow

Question 19

what happens in plant is put in pure water of dilute solution

Answer 19

the contents of the cell have a lower water potential than the external solution, so the cell wall absorbs water (osmosis) and swells up, cytoplasm pushes against wall. They are TURGOR

Question 20

what happens if put in conc. sucrose solution

Answer 20

-lower water potential that cell, will loose water(osmosis) and decrease in volume. cytoplasm doesn’t push and cell is flaccid. Makes plant wilt

Question 21

structure of a stem

Answer 21

starch from leaves are stored in roots
in stem:
-vascular bundle arranged in outer part of stem-xylem(transports water in one direction)
phloem(transports sugars and amino acids in both directions)

xylem and phloem make up the vascular bundle

Question 22

the two stimuli acting on plants

Answer 22

1. direction of light that falls on plant
2. gravity

Question 23

tropism

Answer 23

A growth response of a plant toward or away from a stimulus
-towards=positive
-away=negative

Question 24

geotropism

Answer 24

• a growth response to gravity
  no light under soil so gravity is stimulus
  positive= grows towards direction of gravity
  negative=grows away from gravity

Question 25

phototropism

Answer 25

A growth response to light
positive=grows towards light source
negative=grows away from light source

Question 26

what is a coleoptile

Answer 26

protective sheath that covers leaves as shoot emerges through soil
are used to investigate tropisms

Question 27

the hormone responsible for growth and development of plants

Answer 27

auxin- speeds up rate of growth, found at top of tip of shoots and diffuses to plant
-gathers on shaded side of root and causes cell elongation to enable positive phototropism

Question 28

differences between asexual and sexual reproduction

Answer 28

SEXUAL=
-produces gametes
-fertilization takes place
-genetic variation in offspring
-survival value in changing environment

ASEXUAL=
-no gametes produced
-no fertilization
-no genetically variation in offspring
-survival value in stable environment

Question 29

advantage and disadvantage of sexual reproduction

Answer 29

advantage=
-increases genetic variation
-can adapt to new environments
disadvantages=
-time and energy to find mates
-isolated members of species difficult to reproduce

Question 30

advantages disadvantages of asexual reproduction

Answer 30

advantages=
-population can increase rapidly
-can suit environments quicker
-more time efficient
-reproduction is completed faster
disadvantages=
-limited genetic variation
-vulnerable to changes in conditions
-disease more likely to affect whole population

Question 31

how plants can reproduce asexually

Answer 31

1. runners - fast growing stem that grows horizontally over the soil surface and puts down roots to form new plants
2. cuttings- taking a piece of a shoot and planting in compost to develop

Question 32

sexual reproduction in plants

Answer 32

plants produce haploid gametes

males gametes are in pollen grains
female gametes are egg cells(ova) in ovules

male gametes can be transferred to female gametes through pollination, by wind or insects

fertilization occurs and zygote develops into seed which becomes enclosed in a fruit

Question 33

where are pollen grains produced

Answer 33

in the anther of the stamen

Question 34

where are the ova produces

Answer 34

in the ovules of the ovaries

Question 35

what happens during pollination

Answer 35

pollen grains transferred from to stigma

self pollination = pollen grains transferred to stigma within the same flower or to another flower of the same plant

cross pollination= pollen grains transferred to a different flower

can occur by wind or insects

Question 36

structure of insect pollinated flowers

Answer 36

-stamen enclosed within flower so insect must make contact
-sticky pollen grains
-large petals
-bright colored
-sweet nectar
-larger, sticky grains to stick

Question 37

structure of wind pollinated flower

Answer 37

-exposed stamen, wind can blow away
-feathery stigma
-small petals
-not brightly colored, usually green
-no nectar
-small smooth grains to carry in wind

Question 38

process of fertilization

Answer 38

1.pollen grain forms pollen tube which growth through style into ovule
2.pollen grain nucleus moves down into ovule
3.fuses with ovum nucleus

seed and fruit formation=

1. zygote develops small root and shoot (plumule, radicle)
   2.Other contents of the ovule develop into a food store for the young plant when the seed germinates
2. ovule wall becomes the seed coat

Question 39

what is germination

Answer 39

germinating seeds save food reserves until seedling can carry out photosynthesis

when seeds disperse from parent plant, they are dry

dormancy comes to an end, and germination needs to follow 3 conditions

WOW
water-chemical reaction to take place in solution
oxygen-for respiration
warm temps- for enzymes to act

Question 40

investigation for conditions needed for seed germination

Answer 40

-4 small seeds will grow on wet/dry cotton wool
-tube A=wet cotton wool
-tube B=dry cotton wool
-tube C= boiled water with oil layer
-tube D= wet cotton wool - places in REFIDGERATOR

after a few days
tube A will germinate
no germination in B,C
Tube D will germinate eventually