FLOWERS (PS 13)

Question 1

State the functions of flowers

Answer 1

Flowers are the reproductive plant organs of Angiosperms (flowering plants). They may be showy to attract pollinators or small and pendulous to facilitate wind pollination.

Functions:
- production of the Make and Female gametes (sex cells) ( main role- male gamete in anther, female gamete in an ovule)

• colourful flowers to attract pollinators / dispersing pollen on the wind
• production of fruits and seed.

Question 2

Draw a vertical section of a monocotyledon flower (not grass) & a dicotyledon flower to show where appropriate:

Answer 2

RECEPTACLE 
TEPAL
SEPAL
PETAL
CALYX
COROLLA
NECTARY
ANTHER
FILAMENT
STAMEN
STIGMA
STYLE
OVARY
OVULE

Question 3

External structure of plants

Name 1 external structure of INFLORESCENCE plant and one plant name

Answer 3

EXTERNAL STRUCTURE
Flowers can be held singularly on a pedicel (flower stalk) or in a group- known as an INFLORESCENCE

Could have:
UMBEL
all pedicels attached at same point on the stalk
Allium cepa (onion)
Or
Agapanthus ‘enigma’

SPIKE
Is inflorescence plant where individual flowers are connected to the Rachis.
Acanthus mollis

RACEME
is an unbranched, indeterminate type of inflorescence bearing pedicellate flowers (flowers having short floral stalks called pedicels) along its axis.
Wisteria floribunda

HEAD
head (capitulum) is a short dense spike in which the flowers are borne directly on a broad, flat peduncle, giving the inflorescence the appearance of a single flower, as in the dandelion (Taraxacum).
Helianthus annuus

CORYMB
Unlike in the Umbel, the corymb consists of pedicilate flowers where the length of pedicels of the lower flowers is more than that of the upper ones such that all the flowers come up to the same level. They have an umbrella appearance when seen from the top. Example:
Achillea millefolium

PANICLE
branching out secondary flowers flowers attached on extended pedicel to the rachis
Syringa Vulgaris

Question 4

Name given to flowers that contain both make and female reproductive organs

Answer 4

Hermaphrodite

Question 5

Non sexual parts of a flower

Answer 5

PEDICEL
is the flower stalk, the top of which is an enlarged area called the receptacle

RECEPTACLE
The receptacle holds the whorls (rings) of flower parts (holds the sexual and non sexual parts of the flower)

SEPALS
the sepals form the outermost whorl and serve to protect the flower when it is in bud. They are usually green in colour. The sepals are know collectively as the CALYX. They are not present on all flowers. They are modified leaves which protect inner parts of the flower - only commonly found in most dicots plants that are insect pollinated.

PETALS
The petals (known collectively as the corolla) attract pollinators with their scent, shape and colour. Petals are reduced or absent on wind pollinated plants. When petals are fused together they are known as CORONA e.g Narcissus and Penstemon . Together the COROLLA and CALYX, are known as the PERIANTH, which roughly translates as ‘around the flower’.
Produce honey guides which direct a pollinator into the flower where nectar was present 

NECTARIES
The nectaries, which produce nectar, are located at the base of the petal. The nectar lures insects deep inside the flower, encouraging pollination, as insects brush past the sexual flower parts

Question 6

Sexual flower parts

Answer 6

The MALE part is known as the STAMEN, which consist of two parts, the ANTHER and the FILAMENT.

ANTHER
Upper part of stamen. Usually has 2 loves, each love has two pollen sacs, within which the pollen grain is produced. The male gamete is held within the pollen. The pollen of insect or animal pollinated plants is sticky and larger than that of wind pollinated flowers.

FILAMENT
the filament is a stalk, which holds the anther aloft, for successful pollination.

THE FEMALE SEXUAL PARTS
The female part is the CARPEL: this consist of 3 parts :the ovary , style, stigma.

THE OVARY
is at the base of the carpel and contains one or more OVULES. The female gamete is held within the ovule. Flowers may have several ovaries eg Rubus idaeus (raspberries), or one ovary that contains many ovules eg Pisum sativum pea

THE STYLE
a slender stalk they supports the stigma into perfect position for pollination

THE STIGMA
Is the uppermost part of the carpel. It is designed to receive pollen, and is often sticky or ridged so that pollen adheres to it.

Question 7

differences to Monocot and dicot insect pollinated

Answer 7

In many insect pollinated monocotyledon flowers eg tulipa - there is no difference between the calyx and corolla. This combination is called a TEPAL