4. Seeds

Question 1

Formation of the embryo

Answer 1

Pollen sperm fertilizes the egg, resulting in a zygote
The zygote begins cell division and es polarity, up and a down
-Lower end forms a basal cell and stalk-like suspensors. Anchors the embryo at the micropyle end
-Upper end forms an apical cell, where most of the growth comes from

Question 2

Differentiation of the embryo

Answer 2

Occurs through different planes of cell division
Protoderm becomes the epidermis
Vertical cell division leads to the ground meristem and the procambium( precursor to xylem and phloem)

Question 3

Stages of Seed Development in Dicots:

Answer 3

1. Globular Stage
   * Suspensor – anchors embryo and absorbs food from endo sperm
   * Basal cell
   * Proembryo – becomes the embryo, then the seed
2. Heart shaped stage
3. Torpedo stage
4. Mature embryo

Question 4

Integument

Answer 4

seed coat

Question 5

Funiculus

Answer 5

stalk of the ovule

Question 6

Hilum

Answer 6

scar where the funiculus was attached

Question 7

Micropyle

Answer 7

opening in the integument of the ovule through which the pollen tube enters the embryo

Question 8

Epicotyl

Answer 8

embryonic shoot

Question 9

Plumule

Answer 9

becomes stem and leaves

Question 10

Hypocotyl

Answer 10

region between the shoot and the root

Question 11

Radicle

Answer 11

embryonic root

Question 12

Cotyledon

Answer 12

contain stored food

Question 13

Endosperm

Answer 13

contains stored food outside the embryo but inside the seed coat

Question 14

Scutellum

Answer 14

specialized cotyledon in grasses

Question 15

Coleoptile

Answer 15

sheath of the shoot

Question 16

Coleorhiza

Answer 16

sheath of the radicle

Question 17

Hypogean development

Answer 17

cotyledons remain below ground

Question 18

Epigean development

Answer 18

cotyledons above ground

Question 19

Parts of a dicot seed

Answer 19

Endosperm- absorbed by developing embryo
Fleshy cotyledons
Micropyle
Hilum
Seed coat

Question 20

Parts of a monocot seed

Answer 20

Pericarp
Endosperm
Scutellum
Coleoptile
Plumule
Radicle
Coleorhiza

Question 21

Role of the testa

Answer 21

Provides protection
Critical in monitoring water uptake during seed germination

Question 22

Seed maturation – what occurs?

Answer 22

• Huge amounts of starch, oils, and proteins in endosperm, perisperm, cotyledons
• Desiccation, loss of 90% of its moisture
• Seed coat hardens
• Some are quiescent, resting until exposed to water, some are dormant, won’t grow without special environmental signals, cold or photoperiod

Question 23

Quiescent

Answer 23

A state of inactivity caused by unfavorable external environmental conditions. A seed that does not germinate because the soil is too dry

Question 24

Dormant

Answer 24

A state of inactivity caused by internal physiological factors, regardless of favorable environmental conditions. A seed that won’t germinate even in optimal soil and moisture conditions because it requires a period of cold stratification.

Question 25

Seed germination process –what happens and how does it happen? When is germination complete?

Answer 25

Period between resting and growth stages of the plant
Requires- water, oxygen, and suitable temperature
Most vulnerable stage
Radicle emergence signals the end of germination