Events In Germination Flashcards
How do seeds store food?
They store food in the form of oils, starch (especially in cereals and grasses) and protein (especially in legumes such as peas and beans)
Give some examples of seeds which store food as starch.
Cereals
Grasses
Give some examples of seeds which store food as protein
Legumes such as peas and beans
When does germination begin?
(Step 1)
(3)
Germination begins when the seed absorbs water
Water is absorbed through a tiny hole called the micropyle and through the testa
Water allows enzymes to be activated in the seed
How exactly does the seed absorb water?
It is absorbed through a tiny hole called the micropyle and through the testa
Explain how seeds digest food.
(Step 2)
(4)
In germinating seeds;
- oils are digested to fatty acids and glycerol
- starch is digested to glucose (involves the enzyme amylase)
- proteins are digested to amino acids
What are oils broken down into in seeds?
Oils are digested to fatty acids and glycerol
What is starch broken down into in seeds?
Starch is digested to glucose
What enzyme is involved in the breakdown of starch into glucose?
Amylase
What are proteins broken down into in seeds?
Proteins are digested into amino acids
What happens to the products of digestion in seeds?
Step 3
The products of digestion are moved to the growing embryo (i.e. the plumule and radicle)
What happens to glucose and amino acids in seeds?
Step 4
Glucose and amino acids are used to make new structures such as cell walls and enzymes
What happens to fats and some of the glucose in seeds?
Step 5
The fats and some of the glucose are used in respiration to produce energy
What happens to the seed after respiration has occurred?
Step 6
The dry weight (mass) of the seed falls due to the foods used in respiration
What happens to the embryo after the weight of the food stores falls?
(Step 7)
As the weight of the food stores (i.e. the endosperm and/or the cotyledon(s)) the weight of the embryo increases
Why does the dry weight of the seed fall?
It falls due to the food being used in respiration
What is another word for the dry weight of a seed?
The mass of a seed
What happens after the weight of the embryo begins to increase?
(Step 8)
The radicle bursts through the testa
When does the radicle burst through the testa?
After the weight of the embryo has increased
What does the radicle burst through?
The testa
What happens after the radicle bursts through the testa?
Step 9
The plumule emerges above ground and leaves are produced
When are leaves produced?
When the plumule emerges above ground
What is produced when the plumule merges above ground?
Leaves are produced
What happens after the leaves have been produced?
(Step 10)
(2)
The leaves start to photosynthesise
The dry weight of the seedling increases again
When does the dry weight of the seed increase again?
After the leaves have begun to photosynthesise
What happens to the seedling when the leaves start to photosynthesise?
They dry weight of the seedling increases again
List the events in germination
10 steps
- seed absorbs water - through micropyle and testa - enzymes are activated in the seed
- oils -> fatty acids + glycerol, starch -> glucose, proteins –> amino acids
- products of digestion moved to growing embryo
- glucose and amino acids - new structures - cell walls and enzymes
- Fats and some glucose -> respiration -> energy
- Mass of seed falls - food used in respiration
- Weight of food stores falls - weight of embryo increases
- radicle bursts through the testa
- plumule merges above ground - produces leaves
- leaves - photosynthesise - mass of seedling increases again
