ch 15

Question 1

define reproduction

Answer 1

it is the ability of the organism to produce offspring of their own kind to keep their species

Question 2

define asexual reproduction

Answer 2

one parent cell divides to give 2 daughter cells

Question 3

define gamete

Answer 3

it is a haploid cell containing half the number of chromosomes

Question 4

define fertilization

Answer 4

it is the fusion of male gametes with female gametes to form a zygote

Question 5

define zygote

Answer 5

a diploid cell with contains full no. of chromosomes due to fertilization

Question 6

define sexual reproduction

Answer 6

male parent by meiosis produce sperm (male gamete) and female parent by meiosis produce ovum (female gamete) that fuse together by fertilization to produce zygote

Question 7

advantages of asexual reproduction [4]

Answer 7

-rapid
-simple
-big number of offspring
-keeps good characters

Question 8

disadvantages of asexual reproduction [2]

Answer 8

-no variation
-no evolution

Question 9

advantages of sexual reproduction [2]

Answer 9

-there is variation, more adapted variety survives better in the surronding enviroment and live longer
-there is evolution

Question 10

disadvantages of sexual reproduction [4]

Answer 10

-slow
-complicated
-small number of offspring
-good characters in parents may not be transferred to the offspring

Question 11

3 examples of asexual reproduction

Answer 11

-in bacteria (simple binary fission)
-in bread mould fungus (spore formation)
-in potato tuber (tuber formation)

Question 12

steps of simple binary fission[2]

Answer 12

-one parent bacterial cell makes a copy of DNA
-then divides into 2 daughter cells , identical to each other and to the parent cell

Question 13

steps of spore formation [3]

Answer 13

-hypha grows up and a spornagium is formed on top of hypha containing spores
-sporangium bursts open releasing spores
-if spore meet suitable conditions it grows to form new fungus

Question 14

how does potato plant make both types of reproduction

Answer 14

-sexual reproduction -> by flowers above the soil
-asexual reproduction -> by tuber formation below the soil

Question 15

steps of tuber formation in potato plant [3]

Answer 15

• the stem of potato plants produce branches which grow downwards instaed of upwards
  -leaves make photosynthesis , produce food, transport it to underground stem which store food as starch in swellings called tubers
  -the parent plant dies leaving the tubers in soil , each tuber has eyes and buds, buds grow to form new root and shoot hence a new plant is formed

Question 16

how many potato tubers are formed from one potato plant

Answer 16

10 potato tubers, 10 daughter plants

Question 17

what are the leaves in flower [2]

Answer 17

sepals, green leaves
petals, colored leaves

Question 18

what is the stamen made of

Answer 18

-anther
-filament

Question 19

function of anther

Answer 19

produce pollen grains

Question 20

function of filament [2]

Answer 20

-carry anther
-contain xylem and phloem to supply pollen grains with sucrose and amino acids to produce energy needed for cell division by meiosis

Question 21

function of sepal

Answer 21

protection

Question 22

function of nectar gland

Answer 22

secrete nectar , sugary fluid sucked by insects

Question 23

function of petals [2]

Answer 23

-protects reproductive organs
-attract insects for pollination

Question 24

what is carpel made of [4]

Answer 24

-ovary
-ovules
-stigma
-style

Question 25

function of stigma

Answer 25

recieve pollen grains

Question 26

function of style

Answer 26

carry stigma

Question 27

function of ovary

Answer 27

produce ovules (female gametes)

Question 28

what is receptacle

Answer 28

expanded part of the stem

Question 29

function of receptacle

Answer 29

carry the whole flower

Question 30

define pollination

Answer 30

it means the transfer of pollen grains from anther to stigma

Question 31

types of pollination [2]

Answer 31

-self pollination -cross pollination

Question 32

where does self pollination occure

Answer 32

in bisexual flowers

Question 33

where does cross pollination occur [2]

Answer 33

unisexual and bisexual flowers

Question 34

advantages of self pollination [2]

Answer 34

-dont need wind or insect -no waste of pollen grains

Question 35

disadvantages of self pollination [3]

Answer 35

-less variation -less evolution -less hetrozygous , more homozygous genotypes so bad recessive characters are more likely expressed

Question 36

advantages of cross pollination[3]

Answer 36

-more variation -more evolution -more heterozygous, less homozygous so bad recessive characters are less likely to be expressed

Question 37

disadvantages of cross pollination[2]

Answer 37

-need wind or insect -waste of pollen grains

Question 38

compare wind-pollinated flowers and insect-pollinated flowers in terms of size and nectaries

Answer 38

-wind is smaller in size -wind doesnt have nectaries

Question 39

describe the petals in wind-pollinated flowers

Answer 39

absent, to allow exposure of anther / stigma for easier pollination by wind

Question 40

describe the petals in insect-pollinated flowers [5]

Answer 40

-large -colored -scented -attractive -have guide lines

Question 41

describe the stigma in wind-pollinated flowers [3]

Answer 41

-large -feathery -hanging outside the flower to trap pollen grains

Question 41

describe the stigma in insect-pollinated flowers [3]

Answer 41

-small -sticky -enclosed inside the flower to hold pollen grains from the insect's body

Question 42

describe the anther in wind-pollinated flowers [2]

Answer 42

-hanging outside the flower to catch wind -movable (loosely attached to filament)

Question 43

describe the anther in insect-pollinated flowers [2]

Answer 43

-enclosed inside the flower so that insects can brush them -fixed (firmly attached to filament)

Question 44

describe the pollen grains in wind-pollinated flowers [5]

Answer 44

-light -small -dry -smooth surface, to be easily carried by wind -large in number . due to loss of much pollen grains in air

Question 45

describe the pollen grains in insect-pollinated flowers [5]

Answer 45

-heavy -large -sticky -has spiky surface , to be easily attached to insect's body -less in number

Question 46

how does insect pollination take place [4]

Answer 46

-small insects are attracted to the flower by their color, scent and sweet nectarine -the insect follow the guide lines in the petal to reach the nectarines -as the insect moves inside the flower they brush the anther by their backs or legs, so some of the pollen grains will stick to their bodies -when the insect moves to another flower the pollen grain on its body will stick to the stigma of the second flower leading to pollination

Question 47

steps of fertilization in flowering plants [6]

Answer 47

- after pollination, the pollen grains begin to grow forming a pollen tube which contains the male nucleus -the pollen tube moves down passing through the style and ovary till it reaches the ovules as it moves the pollen tube secretes enzyme which digest a pathaway through the style -the pollen tube enters into the ovule through the micropyle - the pollen tube opens and releases the male nucleus into the ovule which contains the female nucleus -the male and female nuclei fuse together to form zygote -the zygote divides many times to form embryo

Question 47

role of micropyle in fertilization

Answer 47

a pore that allows entry of pollen tube to ovary to deliver the male nucleus to fuse with the female nucleus

Question 47

role of micropyle in germination

Answer 47

a pore that allows entry of water through testa to enter the seed and activate enzymes

Question 47

steps after fertilization [5]

Answer 47

-ovary forms fruit -ovary wall forms fruit wall -ovules forms seeds -ovule wall form seed wall (testa) -rest of flower parts dry and fall off