Section 7 - Reproduction and Inheritance Flashcards Preview

Edexcel GCSE Biology > Section 7 - Reproduction and Inheritance > Flashcards

Flashcards in Section 7 - Reproduction and Inheritance Deck (45)
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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

Describe the process of germination (5)

A
  • Germination can only take place if conditions are suitable, water, oxygen, temperature
  • Seed takes in water and starts to grow using its store of energy
  • The first root starts to grow down into the soil
  • The shoot grows up
  • Extra roots grow and the first green leaves appear
16
Q

How do germinating seeds get energy? (3)

A
  • When a seed starts to germinate, it gets glucose for respiration from its own food store - This gives it the energy it needs to grow - Once the plant has grown enough to produce green leaves, it can get food for energy from photosyenthesis
17
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
18
Q

Describe what is meant by the term insect-pollination (2)

A
  • transfer of pollen by insect - from anther/stamen to stigma
19
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
20
Q

Are human body cells haploid or diploid, and what does this mean (2)

A
  • Diploid
  • Two copies of each chromosome, arranged in pairs
21
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
22
Q

What is DNA (1)

A
  • Long list of instructions on how to put an organism together and make it work
23
Q

What is a gene (2)

A
  • Found inside DNA molecules
  • Genes are chemical instructions that code for a particular protein
24
Q

Why are proteins important (2)

A
  • Control most processes in the body
  • Determine inherited characteristics e.g eye colour
25
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
26
Q

What are the 4 bases and how are they paired (5)

A
  • Adenine
  • Guanine
  • Thymine
  • Cytosine
  • A,T and G,C
27
Q

Name 2 organisms that reproduce asexually, and what is this type of reproduction called (3)

A
  • Bacteria
  • Plants
  • Mitosis
28
Q

What is asexual reproduction (3)

A
  • Involves only one parent
  • Offspring have identical genes to the parent
  • No variation between offspring and parent
29
Q

What is mitosis (3)

A
  • When a cell reproduces itself
  • By splitting to form two cells
  • with identical sets of chromosomes
30
Q

What is the second step of mitosis (3)

A
  • 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
31
Q

What is the third step of mitosis (3)

A
  • 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
32
Q

What is the fourth step of mitosis (2)

A
  • Membranes form around each of sets of chromosomes
  • These become the nuclei of the two new cells
33
Q

What is the final step of mitosis (3)

A
  • Cytoplasm divides
  • Now have two new cells containing exactly the same DNA
  • Genetically identical
34
Q

Apart from asexual reproduction, name two uses for mitosis (2)

A
  • How all plants and animals grow and repair damaged tissue
  • Cloning
35
Q

What is sexual reproduction (3)

A
  • Fusion of male and female gametes
  • Offspring contain a mixture of parents genes
  • Two parents
36
Q

What are gametes and how are they produced (3)

A
  • Produced in sexual reproduction
  • Sperm cells
  • Egg cells
37
Q

Are gametes haploid or diploid and what does this mean (2)

A
  • Haploid
  • In humans, each gamete contains 23 chromosomes
38
Q

What happens at fertilisation (sexual reproduction) (3)

A
  • Male gamete fuses with a female gamete
  • Forms a zygote (fertilised egg)
  • Zygote ends up with a full set of chromosomes
39
Q

After a zygote is formed, what happens to it (2)

A
  • Undergoes cell division by mitosis
  • Develops into an embryo
40
Q

Where does meiosis happen in humans (2)

A
  • Reproductive organs
  • Ovaries and testes
41
Q

Meiosis produces …………….. cells whose chromosomes are …………. (2)

A
  • four haploid
  • not identical
42
Q

What is the first step of meiosis (3)

A
  • 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
43
Q

What is the second step of meiosis (4)

A
  • 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
44
Q

What is the final step of meiosis (5)

A
  • 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
45
Q

Outline 3 differences between mitosis and meiosis (3)

A
  • 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