Botany 1st Chapter

Question 1

What is the ovule attached to within the ovary?

Answer 1

The placenta by means of a stalk called funicle.

Question 2

What does the hilum represent in the ovule structure?

Answer 2

The junction between ovule and funicle.

Question 3

What is the developing ovule fused with the funicle called?

Answer 3

Hilum.

Question 4

What is the initial development of the ovule described as?

Answer 4

A small protuberance of homogenous tissue on the placenta.

Question 5

What is the nucellus primarily composed of?

Answer 5

Abundant reserve food materials.

Question 6

What encloses the nucellus?

Answer 6

One or more protective envelopes called integuments.

Question 7

What is the small opening at the tip of the ovule called?

Answer 7

Micropyle.

Question 8

What is the basal part of the ovule known as?

Answer 8

Chalaza.

Question 9

What does the nucellus generally contain?

Answer 9

A single embryo sac (female gametophyte).

Question 10

What is the process of formation of megaspores from the diploid megaspore mother cell called?

Answer 10

Megasporogenesis.

Question 11

What type of cell is differentiated at the micropylar end of the nucellus?

Answer 11

Megaspore mother cell (2n).

Question 12

How many haploid megaspores are formed from the diploid megaspore mother cell?

Answer 12

Four haploid megaspores.

Question 13

What arrangement do the four haploid megaspores take?

Answer 13

Linear tetrad.

Question 14

In most flowering plants, how many megaspores are functional?

Answer 14

One megaspore.

Question 15

What type of embryo sac is developed from a single haploid megaspore?

Answer 15

Monosporic embryo sac.

Question 16

What is the first cell of the female gametophyte?

Answer 16

Functional megaspore (n).

Question 17

Fill in the blank: The functional megaspore develops into _______.

Answer 17

[female gametophyte (embryo sac)].

Question 18

What are the two ends of the embryo sac?

Answer 18

Micropylar end and chalazal end

The micropylar end is where the egg apparatus is located, while the chalazal end contains the antipodals.

Question 19

What is formed at the micropylar end of the embryo sac?

Answer 19

Three-celled egg apparatus

The egg apparatus consists of two lateral synergids and one egg cell.

Question 20

What is the function of the filiform apparatus?

Answer 20

Guides the pollen tube into the synergids

The filiform apparatus is a special cellular thickening at the micropylar tip of synergids.

Question 21

How many nuclei are present in the embryo sac at the eight nucleate stage?

Answer 21

Eight nuclei

At this stage, six nuclei are surrounded by cell walls, while two polar nuclei remain in the center.

Question 22

What type of cells are formed at the chalazal end of the embryo sac?

Answer 22

Three-celled antipodals

Antipodals are located at the chalazal end and are formed from the remaining cells.

Question 23

What is the composition of the central cell in the embryo sac?

Answer 23

One large central cell with two polar nuclei

The polar nuclei move towards the center of the embryo sac to form this cell.

Question 24

What is a megaspore mother cell also known as?

Answer 24

Nucellus

The megaspore mother cell is responsible for forming the megaspores.

Question 25

Fill in the blank: The embryo sac matures through _______ and a seven-celled stage.

Answer 25

Eight nucleate ## Footnote This is a critical stage in the development of the embryo sac in angiosperms.

Question 26

True or False: The embryo sac consists of three types of cells.

Answer 26

False ## Footnote The embryo sac consists of more than three types of cells, including synergids, egg cell, antipodals, and the central cell.

Question 27

What are synergids?

Answer 27

Cells that assist in pollen tube guidance ## Footnote They are located at the micropylar end of the embryo sac and have specialized structures for this function.

Question 28

What are the stages of megaspore formation?

Answer 28

Megaspore tetrad, megaspore dyad ## Footnote These stages represent the division of the megaspore mother cell before forming functional megaspores.

Question 29

What is megasporogenesis?

Answer 29

The process of formation of haploid megaspores from a megaspore mother cell (2n) ## Footnote Megasporogenesis occurs within the nucellus of the megasporangium.

Question 30

What is the first step in megasporogenesis?

Answer 30

One megaspore mother cell (2n) undergoes meiosis ## Footnote This results in 4 haploid megaspores arranged in linear tetrads.

Question 31

How many functional megaspores are produced from megasporogenesis?

Answer 31

One functional megaspore ## Footnote Three of the four haploid megaspores produced are typically non-functional.

Question 32

Describe the development of the embryo sac during megasporogenesis.

Answer 32

It involves 3 repeated mitotic free nuclear divisions leading to a 2-nucleate and then an 8-nucleate embryo sac ## Footnote Cellularisation and distribution of cells occurs afterward.

Question 33

What types of cells are present in the mature embryo sac?

Answer 33

* 3-celled antipodals * 3-celled egg apparatus (egg cell + 2 lateral synergids) * Central cell with 2 polar nuclei ## Footnote These structures are essential for fertilization and seed development.

Question 34

What is microsporogenesis?

Answer 34

The process of formation of haploid microspores from a microspore mother cell (2n) ## Footnote Microsporogenesis occurs within the microsporangium of the anther.

Question 35

What is the role of the microspore mother cell (PMC) in microsporogenesis?

Answer 35

A number of sporogenous cells become pollen mother cells (PMC) ## Footnote These cells lead to the formation of a large number of microspores or pollen grains.

Question 36

What is the difference between megasporogenesis and microsporogenesis?

Answer 36

Megasporogenesis produces haploid megaspores; microsporogenesis produces haploid microspores ## Footnote Megasporogenesis occurs in the nucellus, while microsporogenesis occurs in the anther.

Question 37

Fill in the blank: The __________ is the ovary part of the gynoecium in megasporogenesis.

Answer 37

Ovary (2n) ## Footnote The ovary supports the development of the embryo sac.

Question 38

True or False: The megasporangium contains a single megaspore mother cell.

Answer 38

True ## Footnote This cell undergoes meiosis to produce haploid megaspores.

Question 39

Fill in the blank: The __________ is formed by the cellularisation and distribution of the nuclei in the embryo sac.

Answer 39

8-nucleate embryo sac ## Footnote This stage is crucial for the eventual formation of gametes.