Chapter 14 Reproduction In Plants Flashcards
Define asexual reproduction:
A process resulting in the production of genetically identical offspring from one parent
Define sexual reproduction:
The process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other and from the parents
Define gamete:
A sex cell
A cell with half the normal number of chromosomes, whose nuclear fuses with the nucleus of another gamete during sexual reproduction
Define fertilisation:
The fusion of the nuclei of two gametes
Define Zygote:
A cell that is formed by the fusion of 2 gametes
Define diploid:
Having 2 complete sets of chromosomes
Define haploid:
Having only a single set of chromosomes
Define mitosis:
Division of a cell nucleus, resulting into genetically identical nuclei
(i.e. with the same number and kind of chromosomes as the parent nucleus)
Define meiosis:
Division of a diploid nucleus, resulting in four genetically different haploid nuclei.
(sometimes called a reduction vision)
Define sepals:
Leaf-like structures that form a ring outside the petals of the flower
Define petals:
Colored structures that attract insects/birds to a flower
Define stamens:
Male parts of a flower
Define filament:
The stalk part of a stamen
Define anther:
The structure at the top of the stamen, inside which pollen grains are made
Define pollen grains:
Small structures which contain the male gametes of a flower
Define carpel:
female part of the flower
Define ovary:
The part of the flower that holds the ovules
Define ovules:
Small structures that contain the female gametes
Define style:
The part of the carpel that connects the stigma to the ovary
Define stigma:
The part of the flower that receives pollen
Define pollination:
The transfer of pollen grains from the male part of the plant (anther of stamen) to the female part of the plant (stigma)
Define self-pollination:
The transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant
Define cross-pollination:
The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
Define seed:
The structure that develops from an ovule after fertilization, it contains an embryo plant
Define dormant:
Inactive, with metabolic reactions taking place very slowly/not at all
Are there gametes involved in asexual reproduction?
No
How do cells divide to produce genetically identical cells?
Through mitosis
What do you call a primitive organism that makes use of asexual reproduction?
Hydra
Name the differences between Asexual and Sexual Reproduction:
Asexual
1) 1 parent
2) genetically identical offspring
3) no variation
Sexual
1) 2 gametes
2) genetically different offspring
3) increased variation
What are chromosomes?
Long threads of DNA found in the nucleus of a cell
Contains a set of instructions = genes
Where do tubers form?
On stems that grow on/under ground
Give 3 examples of asexual reproduction in fungi:
1) fragmentation → piece of fungus breaks off, could develop into new individual
2) budding → unicellular fungi can bud off a new individual (rather like cell division)
3) spores → spores are dispersed by the wind then grow into new individuals
Give 3 examples of asexual reproduction in plants:
1) fragmentation → if a stem/rhizome connecting parts of a plant is broken/dies, the parts of the plant can develop into new individuals
2) budding → a lateral bud n a stem near the soil develop into new plant
3) bulbs/tubers → they can develop into new individual plants
4) artificial cuttings → cutting of a piece of stem, can be introduced to grow roots
These cuttings can then be planted to grow a new individual
5) artificial tissue culture → single plant cells can be grown into an entire plant in the laboratory
What is a Hydra?
A tiny animal
Lives in fresh water
Related to sea anemones
How does a Hydra reproduce?
Reproduces asexually by growing buds which develop into young Hydra before breaking away from the parent
How do animals reproduce asexually?
Budding → a new individual is budded off from the column and then it pulls off to become a new individual
Where are gametes made?
In reproductive organs
What is the male gamete in a plant called?
Pollen
What is the female gamete in plants called:
Ovule
What is the male gamete in animals called?
Sperm
What is the female gamete in animals called?
Ovum
Name the characteristics of male and female gametes in both animals and plants:
→ Male gametes are smaller than female gametes
→ Male gametes are mobile
→ Female gametes are not mobile
What happens during fertilization in plants?
The nuclei of the 2 gametes fuse to from a zygote
Name 1 characteristic about the chromosomes in a zygote:
A zygote has the same number of chromosomes as the parents
Name 1 characteristic about the chromosomes in a zygote:
A zygote has the same number of chromosomes as the parents
How is it possible that the zygote has the same number of chromosomes as the parents?
The gametes are haploid (means they have half the number of chromosomes of the parent)
So when 2 gametes fuse, 2 haploid nuclei fuse to form a diploid nucleus of the zygote with the same number of chromosomes as the parent
True/false: A zygote grows and develops into a new individual that is genetically unique
True, because gametes are only present in sexual reproduction
Each individual produced by sexual reproduction has their own unique genetic information
What does it mean if a flower is a hermaphrodite?
They have both female and male reproductive organs within a single flower
What are the 2 things that flowers are either specialized for?
Wind-pollination
Insect-pollination
What are the characteristics of a flower that is specialized for insect-pollination?
→ bright, colored petals
→ nectar
→ smaller amounts of round, sticky pollen
What are the characteristics of a flower that is specialized for wind-pollination?
→ less bright petal
→ anthers that hang from flower
→ larger amounts of smooth light pollen
What type of flower is particularly specialized for wind-pollination?
Grass flowers
Name 3 general structures of a flower:
→ sepals
→ receptacle
→ pedicel
What is the function of the sepals?
To protect the flower when in bud
Define receptacle:
Area where flower structures attach to expanded end of flower stalk
What is the pedicel?
The flower stalk
Name the male reproductive organ and what it consists of:
Stamen
→ filament
→ anther
How many pollen sacs does the anther have?
4
What is the function of the filament?
It holds the anther in position so that it is accessible to birds, insects and the wind for pollination
Name the female reproductive organ and what it consists of:
Carpel
→ stigma
→ style
→ ovary
→ ovule
How does the structure of the stigma enable its function?
The stigma is a sticky surface so pollen grains can easily attach to it during pollination
What happens to the ovary after fertilization?
Developes into fruit
What happens to the ovule after fertilization?
It developed into seed
What happens during pollination in a flower?
Pollen grains are transferred from the anther to the stigma
What happens when the flower buds open?
The anthers split open so the pollen is made on the outside of the anther
What is the structure of a pollen grain and how does this affect it?
Pollen grains are surrounded by a hard coat so that it can survive in difficult conditions
The coat → protects the male gametes inside of the pollen grains as its carried around from one flower to another
Why is a self-pollinated plant more likely to decline in species if the environment changes rather than a cross-pollinated plant?
The self-pollinated plant will have less variation in its offspring than a cross pollinated plant
So does less able to respond to changes in the environment, overtime
What is an advantage that self-pollinated plants have that cross-pollinated plants do not?
A self-pollinated plant is not reliant on pollinators in the same way as a cross pollinated plant is
Why will a cross pollinated plant have more variation in its offspring then a self-pollinated plant?
Cross pollinated plant has a greater genetic variety of the parents which enables it to have more variation in its offspring
What 4 things should you look out for in an insect-pollinated flower?
→ large, colorful, and sometimes scented petals
→ nectaries producing nectar
→ stamen inside the flowers so the anther, will touch the insect
→ stigma inside the flower, so the pollen will brush off the insect and stick to the stigma

What 4 things should you look out for in a wind-pollinated flower:
→ no petals/very small petals, w.o. bright colours
→ no nectaries
→ long filament so that the anther hangs outside the flower and pollen can be blown away by the wind
→ large feathering stigma outside the flower to catch pollen blown in the wind
Make a flow diagram to show how pollen travels:
Anther → stigma → style → ovary → ovule
What are 3 differences between wind- and insect-pollinated pollen?
wind
1) smaller amount
2) round
3) sticky and/spikey
insect
1) larger amount
2) flattened
3) smooth
What happens after a flower is pollinated?
The male gamete found in pollen grain → grows down style → toward ovule → in ovule nuclei of male and female gamete fuse during fertilisation → zygote is formed → zygote decides by mitosis → forms an embryo in seed (ovule) → eventually germinates
How does the male gamete inside of the pollen grain reach the ovule?
Pollen grain grows a pollen tube (microscopically small tube) down the style of the flower
It then grows through the ovary wall → enters through the micropyle into the ovule
Define micropyle:
A tiny hole in the ovule
What happens during germination?
The testa (seed coat) cracks open → the radicle (1st root) emerges from the seed → where after the plumule (1st leaves) emerges
What are the nutrients stored in seed used for?
Early growth and development
When does the new plant begin to photosynthesise?
When the first leaves are exposed to sunlight
How can a seed survive harsh conditions before it begins to germinate in the right conditions?
When a seed forms → water in it is drawn out → seed is dehydrated → no metabolic reactions can take place → dormant → can survive harsh conditions
What are 3 important conditions that affect the germination of seeds?
1) Temperature
2) Water
3) Oxygen
Why is temperature an important condition affecting the germination of seeds?
→ Temperature affects enzyme activity
→ Reactions in germinating seeds → controlled by enzymes → therefore temperature dependent.
→ germination tends to happen between 20°C and 30°C
Why is water an important condition affecting the germination of seeds?
Water is needed for:
→ the chemical reactions in the germinating seed and growing seedling
→ metabolic changes (such as digestion of starch to sugars and proteins to amino acids)
→ cell growth in the growing seedling
→ photosynthesis and transport as this evening grows
Why is oxygen an important condition that affects the germination of seeds?
→ growth processes → require large amounts of energy → large amount of oxygen used to produce enough ATP → during aerobic respiration
Compare insect-pollinated and wind-pollinated flowers:
