Section 7 - Reproduction and Inheritance Flashcards
(43 cards)
1
Q
A
2
Q
What are the male and female structures in flowering plants? (2)
A
Male - Stamen Female - Carpel
3
Q
What does the stamen consist of; and what do the parts do? (4)
A
Anther - contains pollen grains; which produce male gametes
Filament - stalk that supports the anther
4
Q
What does the carpel consist of; and what do the parts do? (6)
A
Stigma - End bit that pollen grains attach to
Style - Rod like section that supports the stigma
Ovary - Contains female gametes (eggs)
5
Q
What is pollination? (2)
A
- Transfer of pollen from an anther to a stigma
- So that the male gametes can fertilise the female gametes in sexual reproduction
6
Q
What is cross-pollination? (3)
A
- A type of sexual reproduction
- Where pollen is transferred from the anther of one plant to the stigma of another
- Plants that rely on cross pollination rely on things like insects or the wind to help them pollinate
7
Q
How are plants adapted for insect pollination? (4)
A
- Brightly coloured petals : to attract insects
- Scented flowers and nectaries : to attract insects
- Big sticky pollen grains : the grains stick to insects as they go from plant to plant
- Sticky stigma : so any pollen picked up by insects on other plants will stick to the stigma
8
Q
How are plants adapted for wind pollination? (5)
A
- Small, dull petals : to not attract insects
- No nectaries or strong scents : to not attract insects
- A lot of pollen grains : small and light, to be carried by the wind
- Long filaments that hang the anthers outside the flower : so that a lot of pollen gets blown away by the wind
- Large and feathery stigma : to catch pollen as it’s passed away, which often hangs outside the flower
9
Q
How does fertilisation happen in plants? (4)
A
- A pollen grain lands on the stigma of a flower
- usually with help from insects or the wind
- A pollen tube grows out of the pollen grain and down through the style to the ovary
- A nucleus from the male gamete moves down the tube to join with a female gamete in the ovary
10
Q
What are the right conditions for germination; and what will seeds do if the conditions aren’t right? (4)
A
- Water : to activate the enzymes that break down the food reserves in the seed
- Oxygen : For respiration, which provides the energy for growth
- A suitable temperature : For the enzymes inside the seed to work, depends on what type of seed
- Seeds will lie dormant until the conditions around it are right for germination
11
Q
Advantages and disadvantages of taking cuttings from plants (3)
A
- AD : plants can be produced quickly and cheaply
- AD : You can be sure of their characteristics
- DIS : lack of genetic variation; expossure to disease or changes in environmental conditions, all of them will be affected.
12
Q
What is insect pollination (3)
A
- Transfer of pollen
- from anther to stigma
- by insects
13
Q
Give an example of artifical asexual reproduction in plants (3)
A
- Gardeners use cuttings
- Take cuttings from good parent plants
- Plant them to produce clones of the parent plant
14
Q
Give an example of natural asexual reproduction in plants (6)
A
- Strawberry plants
- Parent strawberry plant sends out runners
- Runners are fast growing stems that grow out sideways, just above the ground
- Runners take root at various points a short distance away
- New plants start to grow
- Genetically identical
15
Q
Explain how a plants leaf mesophyll tissue being eaten affects the growth of the plant (3)
A
- Less surface area to absorb sunlight
- Less chloroplasts
- Less light, less photosyenthesis
16
Q
Describe what is meant by the term insect-pollination (2)
A
- transfer of pollen by insect - from anther/stamen to stigma
17
Q
Give two ways in which the structure of a wind pollinated flower would differ from an insect pollinated flower (4)
A
- less bright and smaller petals
- stamens/anthers outside flower
- no nectary
- stigma feathery
18
Q
Are human body cells haploid or diploid, and what does this mean (2)
A
- Diploid
- Two copies of each chromosome, arranged in pairs
19
Q
How many chromosomes does a human cell nucleas contain, and what is the diploid number for a human (2)
A
- 46 chromosomes
- Diploid number 46
20
Q
What is DNA (1)
A
- Long list of instructions on how to put an organism together and make it work
21
Q
What is a gene (2)
A
- Found inside DNA molecules
- Genes are chemical instructions that code for a particular protein
22
Q
Why are proteins important (2)
A
- Control most processes in the body
- Determine inherited characteristics e.g eye colour
23
Q
Describe a DNA molecule (7)
A
- Has two strands coiled together
- In the shape of a double helix
- Two strands are held together by bases
- Adenine (A) Cytosine (C) Guanine (G) Thymine (T)
- Bases are paired A-T and C-G
- This is called complementary base pairing
- DNA is a type of nucleic acid
24
Q
What are the 4 bases and how are they paired (5)
A
- Adenine
- Guanine
- Thymine
- Cytosine
- A,T and G,C
25
Name 2 organisms that reproduce asexually, and what is this type of reproduction called (3)
- Bacteria
- Plants
- Mitosis
26
What is asexual reproduction (3)
- Involves only one parent
- Offspring have identical genes to the parent
- No variation between offspring and parent
27
What is mitosis (3)
- When a cell reproduces itself
- By splitting to form two cells
- with identical sets of chromosomes
28
# DUPLICATE X2
What is the second step of mitosis (3)
- If the cell gets the signal to divide, it needs to duplicate its DNA
- DNA formes X shaped chromosomes
- Each arm of the chromosomes is an exact duplicate of the other
29
What is the third step of mitosis (3)
- Chromosomes then line up at the centre of the cell
- cell fibres pull them apart
- two arms of each chromosome go to opposite ends of the cell
30
# membranes nuclei
What is the fourth step of mitosis (2)
- Membranes form around each of sets of chromosomes
- These become the nuclei of the two new cells
31
What is the final step of mitosis (3)
- Cytoplasm divides
- Now have two new cells containing exactly the same DNA
- Genetically identical
32
Apart from asexual reproduction, name two uses for mitosis (2)
- How all plants and animals grow and repair damaged tissue
- Cloning
33
What is sexual reproduction (3)
- Fusion of male and female gametes
- Offspring contain a mixture of parents genes
- Two parents
34
What are gametes and how are they produced (3)
- Produced in sexual reproduction
- Sperm cells
- Egg cells
35
Are gametes haploid or diploid and what does this mean (2)
- Haploid
- In humans, each gamete contains 23 chromosomes
36
# fuses, forms, set
What happens at fertilisation (sexual reproduction) (3)
- Male gamete fuses with a female gamete
- Forms a zygote (fertilised egg)
- Zygote ends up with a full set of chromosomes
37
After a zygote is formed, what happens to it (2)
- Undergoes cell division by mitosis
- Develops into an embryo
38
Where does meiosis happen in humans (2)
- Reproductive organs
- Ovaries and testes
39
Meiosis produces ................. cells whose chromosomes are ............. (2)
- four haploid
- not identical
40
# duplicates, exact, line
What is the first step of meiosis (3)
- Cell duplicates DNA before dividing
- One arm of each chromosome is an exact copy of the other arm
- In the first division of meiosis, chromosomes line up in pairs in the centre of the cell
41
# pulled, father, mother
What is the second step of meiosis (4)
- Pairs of chromosomes pulled apart
- So each new cell has one copy of each chromosome
- Some of the fathers/mothers chromosomes go into each new cell
- Each new cell will have a mixture of f/m chromosomes, creating variation
42
What is the final step of meiosis (5)
- Second division, chromosomes line up in the centre of the cell
- Arms of the chromosomes are pulled apart
- Left with 4 haploid gametes
- Each only has a single set of chromosomes
- Gametes are genetically different
43
Outline 3 differences between mitosis and meiosis (3)
- Mitosis : no varation between parent offspring, meiosis, variation (mixture of parents genes)
- Mitosis : one parent, meiosis, two parents
- Mitosis : one round of genetic seperation, meiosis, two rounds
