10.1, 10.2 - Reproduction in Plants

Question 1

What are the two main methods of reproduction?

Answer 1

Sexual and Asexual

Question 2

What are chromosomes?

Answer 2

Long threads of DNA found in the nucleus of a cell, containing a set of instructions known as genes.

Question 3

How does asexual reproduction occur?

Answer 3

One parent. The parent organism’s cells divide by a cell division called mitosis. This produces new cells that contain the same genes as the parent cell (genetically identical), and they grow into new organisms.

Question 4

What is an example of asexual reproduction? (explain)

Answer 4

Potatoes using stem tubers. Some of a potato’s stems grow under the ground, and swellings called tubers form on them. Sucrose is transported to them, converted to starch, and stored. These tubers are to be used as food, though some are used to plant underground. They grow shoots and roots to form a new plant.

Question 5

How does sexual reproduction occur? (1)

Answer 5

The parent organism produces sex cells called gametes.

Question 6

What is the process of fertilisation?

Answer 6

Gametes (eggs and sperm), join, and their nuclei fuse together, forming a zygote. This zygote divides again and again, growing into a new organism.

Question 7

What does a zygote contain?

Answer 7

Chromosomes from both parents, any combination of genes.

Question 8

Why are gametes different from ordinary cells?

Answer 8

They only contain half as many chromosomes as usual, so when two fuse, the zygote will have the correct number. In humans, the egg and sperm cells contain 23 chromosomes each, causing the zygote to contain 46 when they fuse at fertilisation.

Question 9

What is a diploid cell?

Answer 9

A cell that contains the full number of chromosomes, two complete sets.

Question 10

What is a haploid cell?

Answer 10

An egg or sperm (gamete) that has only 23 chromosomes (single set). Whent two gametes fuse together, they form a diploid zygote.

Question 11

How are gametes made?

Answer 11

By ordinary cells dividing. Example: human sperm are made when cells in a testis divide. Gametes need to have only half as many chromosomes as their parent cell, so they’re divided by meiosis.

Question 12

What is meiosis?

Answer 12

Meiosis produces new cells with only half as many chromosomes as the parent cell.

Question 13

What is the female gamete?

Answer 13

It is large and doesn’t move much. In humans: egg, In plants: ovule

Question 14

What is a male gamete?

Answer 14

It moves actively in search of the female gamete. In humans, sperm, in flowering plants, pollen grain.

Question 15

What is a hermaphrodite?

Answer 15

An organism that can produce both male and female gametes (earthworms, slugs, etc.)

Question 16

In which way can flowering plants reproduce?

Answer 16

Both sexually and asexually.

Question 17

What are the sepals?

Answer 17

They are on the outside of the flower and they protect the flower while it is a bud. They are normally green.

Question 18

What are petals?

Answer 18

They’re just inside the sepals and attract insects to the flower due to their bright colours.

Question 19

What is the nectary?

Answer 19

A gland that makes a sugary liquid called nextar, that insects feed on.

Question 20

What are stamens?

Answer 20

They are the male parts. Each stamen is made up of a fillament, and an anther at the top. The anthers contain pollen grains, which contain male gametes.

Question 21

What is the female part of the flower?

Answer 21

It’s in the centre. It consists of one or more carpels. A carpel contains an ovary. Inside the ovary are ovules, which contain the female gametes. At the top of the ovary is the style, with stigma at the tip. The stigma catches pollen grains.

Question 22

What does the anther contain?

Answer 22

Four pollen sacs. Some cells around the edge of the sacs divide by meiosis to make pollen grains. When the flower blud opens, the anthers split open. The pollen is now outside of the anther.

Question 23

What does the pollen look like?

Answer 23

A fine powder, often yellow. Each grain is surrounded by a hard coat to survive in difficult conditions and protect the male gametes inside the grains as the pollen is carried to flowers.

Question 24

When does fertilisation in plants occur?

Answer 24

When a pollen grain nucleus fuses with an ovule nucleus.

Question 25

What is the process of pollination?

Answer 25

When the pollen is taken from the anther, to wear it was made, to a stigma. Often carried out by insects. Insects are attracted to the plants’ colour and scent and follow the guide lines to the nectaries, brushing past the anthers as it goes, causing some pollen to stick to its body. The insect then moves to another flower and the pollen picked up sticks to the stigma of this flower, as the stigma is sticky.

Question 26

What is cross pollination?

Answer 26

When the pollen is taken to a flower on a different plant of the same species. If pollen lands on the stigma of a different species of plant, it usually dies.

Question 27

What is self pollination?

Answer 27

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

Question 28

Explain the differences between wind and insect pollinated flowers?

Answer 28

Insect pollinated - large petals (often with guide lines), strongly scented, nectaries, anthers inside flower, stigma inside flower, sticky or spiky pollen grains (sticks to insects
Wind pollinated - small/no petals, no scent, no nectaries, anthers outside flower, stigmas large outside the flower, smooth and light pollen.

Question 29

How does fertilisation in plants occur after pollination?

Answer 29

If the pollen grain lands on the right kind of stigma, it begins to grow a tube. This tube grows down through the style and ovary, towards ovule, and secretes enzymes to digest a pathway through the style. The ovule has one small hole call the micropyle, the tube goes through the micropyle into the ovule. The pollen nucleus travels along the pollen tube, into the ovule, and fuses with the ovule nucleus.

Question 30

What happens to the flower after it’s ovules have been fertilised?

Answer 30

They have all done their job, they wither and fall off.

Question 31

Where is the zygote after fertilisation?

Answer 31

Each ovule contains one, formed at fertilisation, and zygote divides itself by mitosis to form an embryo plant. It is then called a seed.

Question 32

What does a seed contain?

Answer 32

Ovule that has become hard and dry here, forms the testa of the seed.

Question 33

What is inactive or dormant?

Answer 33

The water in it was all drawn out when first formed, so it became dehydrated, causing the seed to go dormant or inactive.

Question 34

What happens when a seed germinates?

Answer 34

It first takes up water through the micropyle. As the water goes into the cotyledons, they swell and eventually burst the testa. Once there’s sufficient water, the enzymes in the cotyledons become active, amylase begins to break down the stored starch molecules to maltose. Proteases break down the protein molecules to amino acids.