Lecture 13: Gymnosperms and Angiosperms

Question 1

Gymnosperms

Answer 1

seed-forming, non- flowering plants (pines, cycads, etc.)

Question 2

Development of pollen and seeds removed _

Answer 2

the requirement for water for reproduction

Question 3

Pollen

Answer 3

Tiny capsule which contains the male gametophyte and the sperm produced by the gametophyte
* Dispersal by wind (sometimes animals)

Question 4

Seed

Answer 4

Sporophyte embryo packaged into a hard-shelled capsule with food
* Dispersal by wind (sometimes animals)

Question 5

Cones

Answer 5

Scaly sporophylls produced by gymnosperms

Question 6

Gymnosperms produces two types of cones

Answer 6

female and male

Question 7

Prefixes used to refer to the gender of the cone structures

Answer 7

• ‘Micro-‘ is the male reproductive structures
• ‘Mega-‘ is the female reproductive structures

Question 8

Male cone

Answer 8

• Male cone are the microsporophylls (2n) which contain the microsporangium (2n)
• Microsporangum (2n) produces microspores (n) via meiosis
• Microspores grow into the male gametophyte (n), and produces the sperm (n)
• Male gametophyte and sperm is packaged into a pollen

Question 9

Female cone

Answer 9

• Female cone are the megasporophylls (2n) which contain the megasporangium (2n)
• Megasporangium (2n) produces megaspores (n) via meiosis
• Megaspores grow into the female gametophyte (n), and produces the egg (n)
• The megasporangia (2n) and the megaspore (n) is contained in the protective integument.

Question 10

Ovule

Answer 10

Integument + megasporangium + megaspore

Question 11

Ovule development into the seed after pollination

Answer 11

• After pollen grain attaches to the ovule (pollination), the pollen tube delivers sperm to the egg to produce the zygote (fertilization).
• The zygote grows into the embryo, which is the ‘baby’ form of the new sporophyte
• Other tissues of the female gametophyte becomes the food supply, packaged into seed
• Integument becomes the seed coat

Question 12

Moss Life Cycle

Answer 12

Zygote grows into sporophyte (2n)
↓
Sporangia (2n)
↓ ( meiosis )
Spores (n)
↓ ↓
M gametophyte (n) F gametophyte (n)
↓ ↓
Fertilized zygote (2n) (Dispersal by Water)

Question 13

Gymnosperm Life Cycle

Answer 13

Seeds grow into sporophyte (2n)
↓ ↓
Male cone Female cone
* Contains * Contains
microsporangia (2n) megasporangia (2n)
↓ ↓ (meiosis)
microspores (n) megaspores (n)
↓ ↓
Male gametophyte Female gametophyte
with sperm (n) with egg (n)
* contained in pollen * contained in ovule
↓ ↓
(Pollen dispersal by wind)
Fertilized zygote (2n) grows into embryo, packaged into seeds

Question 14

Gymnosperm (pines etc.)

Answer 14

• Greek: gymnos-sperma, naked-seed
• Ovule is exposed to the environment
• Upon pollination, ovule develops into seed

Question 15

Angiosperm (flowering plants)

Answer 15

• Greek: angeion-sperma, container-seed
• Ovule is encased inside the ovary
• Upon pollination, ovule develops into the seed, ovary develops into the fruit

Question 16

Some gymnosperms produce a fleshy, fruit-like structure. Is this a true fruit?

Answer 16

Not a true ‘fruit’ since it is not derived from an ovary

Question 17

Angiosperms: Take full advantage of terrestrial environment

Answer 17

• Angiosperms are seed-forming, flower- and fruit-forming plants
• Development of flowers and fruits allowed angiosperm to take full advantage of the terrestrial environment (such as animals)
• Some pollens and seeds (fruits) specialized for dispersal by animals
• Other pollens and seeds (fruits) specialized for more efficient dispersal by wind

Question 18

Flowers have unique structure to facilitate

Answer 18

pollination via animals

Question 19

Sepal

Answer 19

base of the flower, encloses the flower before it opens

Question 20

Petal

Answer 20

brightly coloured portion of the flower to attract pollinators
* Some flowers are wind pollinated

Question 21

Stamen

Answer 21

male reproductive organ
* Anther contains microsporangia to produce pollens
* Filament is the supportive structure with anther on its end

Question 22

Carpel

Answer 22

female reproductive organ
* Stigma is the sticky tip of carpel to capture
pollens
* Style connects the stigma to the ovary
* Ovary is the base of carpel that contains the ovules

Question 23

Ovule

Answer 23

integument + megasporangia + megaspore

Question 24

Angiosperm ovules are contained in

Answer 24

the ovary

Question 25

Pollen grain on anther gets dispersed by

Answer 25

animals / wind

Question 26

Pollen lands on the

Answer 26

stigma of the carpel (pollination) * Pollen tube grows from the pollen to the ovule to deliver the sperm to egg

Question 27

As with gymnosperms, the ovule develops

Answer 27

into the seed that contains the embryo

Question 28

The ovary of the flower develops

Answer 28

into the fruit

Question 29

Flowers life cycle

Answer 29

1. Megasporangium in each ovule produces megaspore. Megaspores grows into female gametophyte which produces egg. 2. Microsporangium in the anther produces microspores. 3. Microspores develops into male gametophytes, which gets packaged into pollen alongside its sperm. Pollen gets delivered to stigma (pollinization) and pollen tube begins to grow. 4. Pollen tube reaches the ovary and delivers sperm to the ovule. 5. Fertilization of egg and sperm into zygote. 6. Zygote develops into the embryo. Other parts of ovule develops into the seed. The ovary develops into the fruit. 7. Seed gets dispersed and grows into the 'mature plant' (sporophyte).

Question 30

Flower diversity

Answer 30

* This diversity is the result of angiosperms taking advantage of the various creatures on terrestrial land to facilitate pollination * ...aside from those which were bred by humans specifically for their shape and colour

Question 31

Fruits develop from __ to (usually) __

Answer 31

ovaries encase the seed * Protects the seeds and help with dispersal

Question 32

Fruits can be

Answer 32

fleshy or dry * Fleshy fruits: tomatoes, plums, grapes, etc. * Dry fruits: beans, nuts, grains of rice, etc.

Question 33

Fruits facilitate dispersal of seeds, with the most common methods being

Answer 33

Dispersal by animals Dispersal by wind

Question 34

Dispersal by animals

Answer 34

* Some fruits gets dispersed by animals * Eaten by animals, and the undigested seed gets released with the feces * Stored underground by animals (and gets forgotten) * Sticks on to animals to get carried around

Question 35

Dispersal by wind

Answer 35

* Some fruits are specialized for wind dispersal * For example, dandelion fruit and the maple fruit which have a wing-like structure to glide in wind

Question 36

Different types of fruits

Answer 36

* Simple fruit * Aggregate fruit * Multiple fruit * Accessory fruit

Question 37

Simple fruit

Answer 37

*Derived from a single carpel or several fused carpels

Question 38

Aggregate fruit

Answer 38

* Derived from a single flower with a group of individual carpels each forming a small fruitlet * Fruitlets become clustered together

Question 39

Multiple fruit

Answer 39

* Derived from group of flowers clustered together * Ovaries mature and fuse together into 'one' fruit

Question 40

Accessory fruit

Answer 40

* Other parts of flower develops into what humans perceive as the 'fruit'

Question 41

Apple is an accessory fruit

Answer 41

* The 'core' of the apple is its actual fruit, developed from the ovule * Majority of the fleshy, edible portion is derived from the receptacle tissue which surrounds the ovule

Question 42

Dandelions produce

Answer 42

multiple, clustered fruits from multiple, clustered flowers

Question 43

Dandelion fruit is specialized for

Answer 43

wind dispersal, floating in air * The white wings are called pappus

Question 44

Is the Dandelion flower a single flower?

Answer 44

* The dandelion 'flower' is not a single flower * It is many small florets clustered together * Each seed-head contains about 40–100 florets

Question 45

Roots

Answer 45

* Anchors vascular plant in soil and absorbs mineral and water * Often stores carbohydrates and other reserves for the plant to use * Carrots stores food directly in their roots (root veggies) * Potatoes are tubers, which store food in specialized structures which developed from parts of their root

Question 46

Roots and the nitrogen cycle

Answer 46

* Plants use roots to absorb nitrogenous compounds in soil * Nitrate (NO3-) is what's mainly absorbed via the root, plus some ammonium (NH4+) * Soil-living, nitrogen fixing bacteria fix nitrogen gas in the atmosphere (N2) to ammonia (NH3) * Ammonia gets converted to ammonium in soil * Some of these nitrogen fixing bacteria are free living * Others form a symbiotic relationship with certain types of plants

Question 47

Nitrogen cycle & Rhizobium sp.

Answer 47

* Bacteria of Rhizobium sp. coexist inside specialized root nodules of their host plant * Growing plant invite Rhizobium sp. to infect their root, while the bacteria also emits chemicals to facilitate the process. * The infected area develops into nodules for Rhizobium to live inside. * A vascular system is established between the nodule and root for nutrient exchange.

Question 48

Why is Rhizobium sp. necessary in context of the nitrogen cycle

Answer 48

* Nodule provides an anaerobic environment for Rhizobium to fix nitrogen * Plant also provides other nutrients to keep Rhizobia population healthy * Rhizobium provides the plant with fixed nitrogen * Many species of legume plants can form this mutualistic relationship * Beans, lentils, chickpeas, alfalfa, clover

Question 49

Crop rotation

Answer 49

* Many commercially important crops such as wheat absorb nitrogen from soil * Growing the same crop in the same field over many years in a row depletes essential nutrients (monocropping) * Other crops such as legumes can add nitrogen to soil via their mutualistic nitrogen- fixing bacteria

Question 50

Crop rotation definition

Answer 50

Plant nitrogen-absorbing crops and legumes in a rotation to help sustain the nutrient content of the field

Question 51

Three field system

Answer 51

* First field: Nitrogen-depleting crops such as wheat/rye * Second field: Legumes such as peas and beans * Third field: No crop planted. The field gets overgrown by weeds. Animals are grazed on this land to add more nutrients via their feces.

Question 52

Why is the Three Field System useful

Answer 52

* Crop rotation drastically increases the amount of crop yield while reducing the need for artificial fertilizers * Crop rotation was a key innovation for human society to sustain a high population