Chapter 14:reproduction in plants

Question 1

describe asexual reproduction

Answer 1

a process resulting in the production of genetically identical offspring from one parent

Question 2

describe sexual reproduction

Answer 2

a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that genetically different from eachother

Question 3

Example of asexual reproduction

Answer 3

1- bacteria
2- plants
3-an animal cell called hydra

Question 4

how does bacteria reproduce asexually

Answer 4

Bacteria produces exact genetic copies of themselves in a type of asexual reproduction

Question 5

how do plants reproduce asexually

Answer 5

They reproduce using bulbs and tubers,these are food storage organs which budding can occur producing new planets which generally are identical to the parent plant

Question 6

how does “hydra” reproduce asexually

Answer 6

By growing buds which develop into young hydra before breaking away from the parent

Question 7

Advantages of asexual reproduction for species in the wild

Answer 7

1-if an organism is well adapted to its environment,then all of its offspring’s will also be well adapted because they are genetically identical to their parents
2-Asexual reproduction requires only one parent, so when the organism is rare, it will be able to reproduce even if there is no possible partner nearby.
3-asexual reproduction can often be faster than sexual reproduction, producing more young in a shorter period of time

Question 8

Advantages of asexual reproduction for crops

Answer 8

1- the grower can produce large number of genetically identical plants so that buyers know exactly what characteristics a plant will have
2-all plants will grow to the same height and ripen at the same time making harvesting and marketing easier

Question 9

Disadvantages of asexual reproduction

Answer 9

1- limited genetic variation in population
2-population is vulnerable to changes in the conditions and may only be suited for one habitat
3-diseases are likely to affect the whole population as there is no genetic variation

Question 10

define fertilisation

Answer 10

the fusion of the nuclei of two gametes

Question 11

define gamete

Answer 11

a gemete is a sex cell which contains only one of each kind of chromosomes

Question 12

Why does gamete have only half as many chromosomes as usual

Answer 12

so that when two of them fuse together,the zygote forms a correct number of chromosomes

Question 13

how many chromosomes does a human body contain

Answer 13

46 chromosomes (23 pairs)

Question 14

Give two examples of gametes

Answer 14

Egg cell and sperm cell

Question 15

define diploid

Answer 15

having two complete sets of chromosomes (a zygote)

Question 16

Define haploid

Answer 16

having only a single set of chromosomes ( a gamete)

Question 17

define mitosis

Answer 17

Division of a cell nucleus resulting in two genetically identical nuclei

Question 18

define meiosis

Answer 18

Division of a diploid nucleus, resulting in four genetically different haploid nuclei.

Question 19

define a hermaphrodite

Answer 19

an organism which produces both make and female gametes

Question 20

Advantages of sexual reproduction

Answer 20

1- increase genetic variation
2- the species can adapt to new environment due to variation,giving them a survival advantage
3- diseases less likely to affect population

Question 21

Disadvantages of sexual reproduction

Answer 21

1-takes time and energy to find mates
2- difficult for isolated members of the species to reproduce

Question 22

name the parts of a flower

Answer 22

The carpel ( stigma,style,ovary,ovule)
Receptacle
Flower stalk
Sepal
Nectary
Petal
Stamen (anther,filament)

Question 23

Function of sepal

Answer 23

Leaf like structures that form a ring outside the petals of a flower

Question 24

Function of petals

Answer 24

coloured structures that attract insects or birds to a flower

Question 25

Function of stamens

Answer 25

The male parts of a flower

Question 26

The function of filament

Answer 26

the ‘stalk’ part of a stamen

Question 27

The function of anther

Answer 27

The structure at the top of a stamen inside which pollen grains are made

Question 28

Function of pollen grains

Answer 28

Small structures which contains the male gametes of a flower

Question 29

Function of carpel

Answer 29

The female part of a flower

Question 30

Function of ovary

Answer 30

the part of the flower that holds the ovules

Question 31

function of ovules

Answer 31

Small structures that contains the female gametes

Question 32

Function of style

Answer 32

The part of a carpel that connects the stigma to the ovary

Question 33

Function of stigma

Answer 33

The part of a flower that receives pollen

Question 34

define pollination

Answer 34

the transfer of pollen grains from the male part of the plant to the female part of the plants

Question 35

what is wind pollination

Answer 35

Wind pollination occurs when the pollen from once plant is transferred to the stigma of another plant of the same species

Question 36

name 7 characteristics of insect polluted flower

Answer 36

1- large,conspicuous petals,often with guide lines
2- often strongly scented
3-often have nectaries at the base of petals
4-anther inside flower,where insect has to brush past them to reach nectar
5-stigma inside flower,where insect has to brush past it to reach nectar
6-sticky or spiky pollen grains,which stick to insects
7- large quantities of pollen are made because some will be eaten and some will be delivered to the wrong flower

Question 37

name 7 characteristics of wind pollinated flower

Answer 37

1- small,inconspicuous petals,or no petals at all
2- no scent
3- no nectaries
4- another’s dang,e outside the flower,where they catch the wind
5- stigmas large and feathery and dang.s outside the flower,where pollen in the air may land on it
6- smooth,light pollen which can be blown in the wind
7-very large quantities of pollen made,because most will be blown away and lost

Question 38

Define self pollination

Answer 38

The transfer of pollen grains from the anther of a flower to the stigma of the same flower,or a different flower or the same plant

Question 39

Define cross pollination

Answer 39

The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

Question 40

When does fertilisation occur

Answer 40

Fertilisation occurs when a pollen nucleus fuses with an ovum nucleus in the ovule

Question 41

How does fertilisation occur

Answer 41

-If the pollen grain has landed on the right kind of stigma, it begins to grow a tube.
-the pollen tube grows down through the style and the ovary,towards the ovule.
-it’s secret enzymes that digest a pathway through the style.
-the pollen tube grows through the micropyle,into the ovule
-the pollen nucleus travels along the pollen tube and into the ovule and fuses with the ovule nucleus.
-fertilisation has taken place

Question 42

Advantage of self pollination

Answer 42

-the plant does not have to reply on pollinators to transfer its pollen,pollen can simply fall from the anther onto the stigma
-if the plant is already well adapted to its environment,then it’s offspring are also likely to be well adapted

Question 43

Advantages of cross pollination

Answer 43

-there is more genetic variation among the offspring,so there is a greater change of at least some of them being able to survive if there are changes in the environment

Question 44

Define germination

Answer 44

Germination is the start of growth in the seed

Question 45

Name the 3 factors required for successful germination

Answer 45

Water-it allows the seed to swell up and the enzymes in the embryo to start working so that growth can occur
Oxygen-so that energy can be released for germination
Warmth-germination improves as temperature rises as the reactions which take place are controlled by enzymes

Question 46

Write down the method to investigate the conditions necessary for the germination of seeds

Answer 46

1- set up 4 boiling tubes each containing 10 cress seeds on cotton wool
2-leave tubes in set environment for a period of time:A,B and C incubated at 20 degrees and D placed in a fridge at 4 degrees
3-compare results and see which tube has the greatest number of germinated seeds