Section 7 - Reproduction and Inheritance Flashcards Preview

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Flashcards in Section 7 - Reproduction and Inheritance Deck (43)
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What are the male and female structures in flowering plants? (2)

Male - Stamen Female - Carpel

3

What does the stamen consist of; and what do the parts do? (4)

Anther - contains pollen grains; which produce male gametes

Filament - stalk that supports the anther

4

What does the carpel consist of; and what do the parts do? (6)

Stigma - End bit that pollen grains attach to

Style - Rod like section that supports the stigma

Ovary - Contains female gametes (eggs)

5

What is pollination? (2)

- Transfer of pollen from an anther to a stigma

- So that the male gametes can fertilise the female gametes in sexual reproduction

6

What is cross-pollination? (3)

- 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

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How are plants adapted for insect pollination? (4)

- 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

How are plants adapted for wind pollination? (5)

- 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

How does fertilisation happen in plants? (4)

- 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

What are the right conditions for germination; and what will seeds do if the conditions aren't right? (4)

- 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

Advantages and disadvantages of taking cuttings from plants (3)

- 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.

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What is insect pollination (3)

- Transfer of pollen 

- from anther to stigma

- by insects

13

Give an example of artifical asexual reproduction in plants (3)

- Gardeners use cuttings

- Take cuttings from good parent plants

- Plant them to produce clones of the parent plant

14

Give an example of natural asexual reproduction in plants (6)

- 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

Explain how a plants leaf mesophyll tissue being eaten affects the growth of the plant (3)

- Less surface area to absorb sunlight

- Less chloroplasts

- Less light, less photosyenthesis

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

- transfer of pollen by insect - from anther/stamen to stigma

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Give two ways in which the structure of a wind pollinated flower would differ from an insect pollinated flower (4)

- less bright and smaller petals

- stamens/anthers outside flower

- no nectary

- stigma feathery

18

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

- Diploid

- Two copies of each chromosome, arranged in pairs

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How many chromosomes does a human cell nucleas contain, and what is the diploid number for a human (2)

- 46 chromosomes

- Diploid number 46

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What is DNA (1)

- Long list of instructions on how to put an organism together and make it work

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What is a gene (2)

- Found inside DNA molecules

- Genes are chemical instructions that code for a particular protein

22

Why are proteins important (2)

-  Control most processes in the body

- Determine inherited characteristics e.g eye colour

23

Describe a DNA molecule (7)

- 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

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

- 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

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What is asexual reproduction (3)

- Involves only one parent

- Offspring have identical genes to the parent

- No variation between offspring and parent

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What is mitosis (3)

- When a cell reproduces itself

- By splitting to form two cells

- with identical sets of chromosomes

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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

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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

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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