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Biology Edexcel > 4th Form > Flashcards

4th Form Flashcards

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1
Q

Producer

A

organisms which make their own food

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2
Q

Consumer

A

Organisms which eat other living things

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3
Q

Decomposer

A

Organisms which secrete digestive enzymes to decay dead organic matter to obtain their food; they help to recycle nutrients

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4
Q

Population

A

The total number of individuals of one species in a particular habitat at a particular time.

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5
Q

Give some reasons for energy loss between trophic levels

A

Not al the organism is eaten
Not all the organism is digested
Some materials were respired (cell division)

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6
Q

Decomposers to Atmosphere

A

Respiration

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7
Q

Atmosphere to plants

A

Photosynthesis

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8
Q

Plant to decomposer

A

Death

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9
Q

Plant to atmosphere

A

Respiration

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10
Q

Fossil Fuels to atmosphere

A

Burning

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11
Q

Plants to animals

A

Feeding

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12
Q

Define Nitrogen Fixation

A

Nitrogen-fixing bacteria in the soil and roots of legume plants absorb nitrogen and reduce it to make ammonia.

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13
Q

Define nitrification

A

Ammonia converted to nitrites and nitrates by nitrifying bacteria.

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14
Q

Define denitrificaiton

A

Nitrates are converted to nitrogen gas

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15
Q

Define decomposition

A

Protein in dead plants and animals is broken down.

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16
Q

Define ammonification

A

The process of converting natural nitrogen compounds into ammonia.

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17
Q

How is the relationship between nitrogen fixing bacteria living on root nodules and the plant mutualistic?

A

the bacteria receive glucose from the plant, while the plant absorbs ammonia from the bacteria in the nodule.

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18
Q

2 carbohydrates found in plants

A

Starch, cellulose

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19
Q

The nitrogen in a nitrate ion in the soil can become the nitrogen in a protein molecule in an animal- explain how this happens

A

Assimilation – nitrates from the soil are absorbed by the roots and are used to make amino acids and proteins which are incorporated into the plants. Animals then eat the plants and the nitrogen in the plants is transferred to proteins in the animal.

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20
Q

Animal to atmosphere

A

death

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21
Q

Fossil fuels to factorys

A

Extraction

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22
Q

Factorys to atmosphere

A

Combustion

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23
Q

Eutrophication + consequences

A

When a large number of algae is growing on the water surface
Low oxygen level suffocates fish
More anearobic bacteria- stagnant/ smelly water

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24
Q

Explain how chemical fertilisers increase crop yields

A

Nitrgon needed to produce ATP
Chemical fertilisers have nitrogen
Nitrogen is needed to make amino acids, proteins and artifical enzymes
DNA and enzymes are essential for cell reproduction

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25
Q

Biome

A

Large areas dominated by a specific type of vegetation

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26
Q

Define greenhouse gas

A

A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect.

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27
Q

Mitosis differences as opposed to meiosis

A

Produces genetically identical daughter cells
Produces two cells
Involves one division
Produces diploid cells in humans
Keeps the same chromosome number

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28
Q

Meiosis differences

A

Produces genetically non-identical
daughter cells
Produces four cells
Involves two cell divisions
Produces haploid cells in humans

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29
Q

Describe the steps of mitosis

A

1.The cell grows
2.The DNA replicates to form two copies of each chromosome. These copies are joined together at a single point (the centromere).
2. The nuclear membrane breaks down. The chromosomes line up across the centre of the cell, attached to special spindle fibres
3. The chromatids (copies of chromosomes) are pulled apart and move to opposite ends of the cell.
4. The cytoplasm and cell membrane divides to form two identical cells.

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30
Q

Describe steps for meiosis

A

1.
The DNA replicates to form a copie of each chromosone,
2.
The nuclear membrane breaks down. The homologous pairs of chromosomes join together.
3.
The homologous pairs of chromosomes exchange sections of DNA. They then attach to the
spindle fibres in pairs, at the centre of the cell.
4.
The homologous pairs of chromosomes are pulled apart and move to opposite ends of the cell. The cell divides.
5.
The chromosomes line up along the centre of the cell, attached to the spindle fibres. The
chromatids separate and move to opposite ends of the cell. Each cell divides again.

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31
Q

Ovary

A

Where egg cells are formed by meiosis (in the follicle). Produces the hormones oestrogen and progesterone.

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32
Q

Oviduct

A

Egg cells travel down this to the uterus. Lined with cilia which move the cell. Site of fertilisation

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33
Q

Uterus

A

A lining forms in the uterus, where the embryo will implant.
The foetus develops in the uterus, which has a thick muscular wall. This contracts during labour.

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34
Q

Cervix

A

Narrow opening to the uterus. This dilates (widens) during labour, to allow the baby to be born.

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35
Q

Testes

A

where sperm cells are formed by meiosis. Produces the hormone testosterone.

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36
Q

Prostate Gland

A

Release liquids into the sperm duct, which mixes
with the sperm cells to form semen. The liquid provides nutrients to the sperm.

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37
Q

Male reproductive system

A
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38
Q

Female reproductive system

A
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39
Q

role of amniotic fluid

A

protection from mechanical shocks, tempurature chanches

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40
Q

Role of placenta

A

Nutrient movement
Transportation of metabolic wastes
(all via diffusion)

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41
Q

Why do the circulatory systems of the mother and foetus not mix?

A
  1. Mothers white blood cells might attack the babys blood
  2. Mother has higher blood pressure
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42
Q

Boys puberty changes

A

Deeper voice
Broader shoulders
Pubic hair

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43
Q

Girls puberty changes

A

Pubic hair
menstrual cycle begins
Deeper voice

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44
Q

FSH- gland , effect, stage released

A

Pituitary gland,
eggs matures and follice develops,
released start of ovulation/ stage 3

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45
Q

Oestrogen- gland, effect, stage released

A

Ovary, inhibits FSH production, released start of ovulation ( stage 3)

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46
Q

LH- gland, effect, stage released

A

pituitary gland, follicle releases ovum into oviduct+follicle turns into corpus luteum, released start of stage 3 (ovulation)

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47
Q

What hormone does the follicle produce? What Hormone does the corpus luteum produce?

A

Follicle- Oestrogen. Corpus Luteum- Progesterone

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48
Q

Progesterone -gland, effect, stage released

A

Ovary, FSH and LH inhibited+ uterus lining maintained, after ovulation/ stage 4

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49
Q

3 methods of asexual reproduction in plants

A

Tubers
Runners
Bulbs
Cuttings (artifical)

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50
Q

Where is pollen produced?

A

Anther

51
Q

What is the anther?

A

The part of the stamen where pollen is produced.

52
Q

Where are ova produced?

A

Ovules

53
Q

What is the carpel?

A

The part of the flower where the Ovules are

54
Q

Insect vs wind pollinated flowers

A

Stamen- enclosed within flower vs Stamen- Exposed outside of petals
Stigma-enclosed within flower and sticky vs exposed outside of petals, often ‘feathery’
Petals Large and brightly coloured vs small, usually green
Nectaries Present - produce sugary fluid to attract insects
vs Absent

55
Q

Plant diagram.

A
56
Q

Stages of plant fertilisation

A
  1. In plants pollen grains are deposited onto the stigma.
  2. The pollen grain goes down a pollen tube which goes down through the style.
  3. Enzymes are secreted at the tip of the tube which digest the tissues of the style.
  4. When the tube reaches an ovule the male gamete travels through the tube entering the ovule through a small hole called the micropyle.
  5. It then fuses with the female gamete (ovum) in the process of fertilisation.
  6. The fertilised ovum divides by mitosis to form the embryo
  7. The ovule develops into the seed.
  8. The ovary develops into the fruit
57
Q

Diffusion definition

A

Diffusion is the random movement of particles from an area of higher concentration to an area of lower concentration.

58
Q

Osmosis Definition

A

Osmosis is the net diffusion of free water molecules from an
area of high water concentration to an area of low water concentration across a partially permeable membrane

59
Q

Osmosis Diagram in plant and animal cells

A
60
Q

Active transport definition

A

Active Transport is the movement of molecules from an area of low concentration to an area of high concentration using ATP

61
Q

What does the xylem transport and why are the transported substances essential for a plant?

A

Transports water and mineral
ions from the roots to the leaves.

Nitrate ions are needed to make
amino acids and proteins

Magnesium ions are needed to
make chlorophyll

62
Q

What makes the xylem cell was waterproof

A

Cell wall contains lignin -
waterproof

63
Q

Describe the structure of the xylem

A

Made up of thick walled dead
cells which contain no cytoplasm -
they are completely hollow and
arranged end to end
End wall are broken down

64
Q

Describe the structure of the phloem

A

Consists of living cells.
Tubes are formed by cells
arranged end to end but have
cell walls made of cellulose.

65
Q

What does the ploem transport and why are the transported substances essential?

A

Sucrose, Amino acids. Essential for respiration.

66
Q

Where does the ploem transport it’s materials?

A

Phloem transports sucrose and
amino acids from the leaves
(where they are made) to the
growing points (eg the tips of
the shoot and flowers) or
storage areas (such as the roots
or bulbs).

67
Q

What is transpiration ?

A

Transpiration is the evaporation of water from the surface of a plant

68
Q

Give 4 factors that affect transpiration

A

Tempurature
Wind speed
Humidity
Light

69
Q

How are root hair cells adapted for diffusion?

A

Thin walled for shorter diffusion distance
Hair like extension for greater SA

70
Q

Functions of transpiration

A

To carry mineral ions to the leaves for the synthesis of amino acid and chlorophyll.
To keep turgor pressure high in leaf cells, holding the leaves up.
Evaporation cools the leaves.
Supplies water for photosynthesis

71
Q

Name of the movement of contents in plants up or down

A

Translocation

72
Q

What happens to the stomata in light and dark

A

Light- the Guard cells open and the stomata beomce turgid
Dark- THe guard cells close and become flacid

73
Q

Why do the stomata open in Light?

A

In the light the guard cells photosynthesise. The concentration of sugars increases, the water potential in the guard cells falls and so water moves into the guard cells by osmosis.
They become turgid (swollen) - this causes the guard cells to become banana shaped, due to the inflexible inner cell wall, and opens the stomata.

74
Q

What flows through the sieve tube?

A

A concentrated solution of amino acids and sucrose

75
Q

Carbon dioxide- where is it formed, how is it made, and where is it excreted

A

Formed in respiring cells, made via respiration, excreted via the lungs

76
Q

Urea- where is it made, how it it made, and where is it excreted

A

Liver cells, deamination, excreted through kidneys and skin.

77
Q

Where are amino acids filtered in?

A

hepatic artery and hepatic portal vein.

78
Q

Describe the areas of the kidney

A

Around the outside and a lighter colour is the
cortex. In the middle are the triangular
shaped medulla and finally in the centre is
the pelvis.

79
Q

What are the role of the nephrons

A

To filter blood

80
Q

Describe the process of Ultrafiltration

A
  1. Blood is pumped at very high pressure. This pressure forces small molecules such as urea, glucose, amino acids and salts out of the capillaries of the glomerulus and into the Bowman’s Capsule. This forms the glomerular filtrate. 2. Larger molecules like proteins or red blood cells are too big to fit across the capillary walls
    and therefore stay in the blood.
81
Q

Describe selective reabsorbtion

A

The filtrate in the Bowmans capsule travels to the proximal convoluted tubule (PCT). However it contains a lot of useful materials such as glucose which would be wasted unless they were recovered. There are specialised cells within the walls of the Proximal Convoluted Tubule. These move the useful materials back into the blood stream. Initially molecules will move by diffusion, but some substances are also moved against a concentration gradient using ATP. This is called active transport

82
Q

Describe Water reabsorbtion in the loop of Henle

A

Ascending tube absorbs Na and Cl- creates a salty environment. Decensing tube lets water osmose into the Saline solution.

83
Q

What do the osmoreceptors do?

A

Release ADH ( turns collecting tube permeable to allow for more water absorbtion when dehydrated)

84
Q

Why is urine more dilute when people are hydrated?

A

The osmoreceptors stop releasing ADH and so all the water is moved into the Urea.

85
Q

How is the leaf specialised for gas exchange?

A

The leaf is thin, so the diffusion distance is short
It has a large surface area, increasing no. of stomata so gases can diffuse quicker
The guard cells form the stomata and can change shape, altering the size of the stomata
The stomata close to reduce water loss

86
Q

Where is Co2 made, how is it made, and where is it removed?

A

Made in respiring cells, via respiration, removed via lungs

87
Q

Where is Urea made, how is it made, and where is it removed?

A

Made in Liver cells, made via the breakdown of amino acids, and removed through the kidneys and skin.

88
Q

Functions of transpiration stream

A

To carry mineral ions to the leaves
To keep turgor pressure high
Evaporation cools the leaves
Supplies water for photosynthesis

89
Q

What could be used to demonstrate a partially permeable membrane in investigating factors of osmosis and and diffusion

A

Visking Tubing

90
Q

What is a stimulus

A

Change in surroundings

91
Q

Receptor

A

The organ that detects the change

92
Q

Effector

A

Muscles that respond to the stimulus

93
Q

Central nervous system

A

Consists to the brain and spinal cord. Co-ordinates nervous reflexes like moving+reflexes

94
Q

Peripheral Nervous system

A

Contains the nerves that send impulses to the effectors

95
Q

Name the 3 types of Neurones

A

Sensory, relay, motor

96
Q

timeline of stimulus to effector

A

receptors detect a stimulus,
stimulus to receptor
receptors to sensory neuron
sensory neuron to brain
brain to relay neuron
relay neuron to motor neuron
motor neuron to effector

97
Q

Nucleus

A

Contains genetic material

98
Q

Dendrite

A

Connections that link to other neurons

99
Q

Axon

A

The section electrical impulses travel across

100
Q

Myelin sheath

A

Insulates Axon and speeds up electrical impulses

101
Q

Name the 2 muscles in the Iris and what they do in different light conditions

A

Radial (contract in dim and relax in bright) Circular (contract in bright and relax in dim)

102
Q

Describe the process that occurs in the eye when looking at an object far away

A
  1. Relaxes ciliary muscles
  2. So the suspension ligament is pulled tight
  3. So the lenses are stretched thin
  4. So there is less light refraction (light rays are parallel so no need for high refraction)
103
Q

Describe the process that occurs in the eye when looking at an object close up

A
  1. contracts ciliary muscles
  2. So the suspension ligament is slacker
  3. So the lenses are thicker
  4. So there is more light refraction (light rays come at a wide angle so high refraction needed)
104
Q

Endocrine system vs Nervous system speed of action

A

Endoctrine is slow, nervous is fast

105
Q

Endocrine system vs Nervous system type of message

A

Endoctrine is chemical while nervous is via electrical impulse

106
Q

Endocrine system vs Nervous system transport method

A

Endocrine system is via the plasma in blood the nervous system is along neurones

107
Q

Endocrine system vs Nervous system response to signal

A

Endocrine is sends to the whole body but only target cells respond and Nervous is directly sent to a muscle or gland

108
Q

Endocrine system vs Nervous system role

A

Endocrine controls long term processes like growth nervous is for a fast response

109
Q

Name the 6 major glands in the human body

A

Thyroid gland
Brain
Pancreas
Testis
Ovary
Adrenal glands

110
Q

Insulin- gland and function

A

Pancreas- manages blood sugar levels by conversions of glucose into glycogen

111
Q

ADH- gland and function

A

Pituitary gland- water regulation via the collecting duct

112
Q

Oestrogen- gland and function

A

Ovary- Inhibits FSH
Stimulates LH
Thickens Uterus lining

113
Q

Progesterone- gland and function

A

Corpus Luteum-
LH and FSH inhibited
Maintains uterus lining

114
Q

Testosterone gland and function

A

Testes- forms male secondary characteristics

115
Q

Adrenaline-gland and function

A

Adrenal gland-
Increase heart rate and breathing for flight or flight mechanism

116
Q

FSH-gland and function

A

Pituitary gland-
Ovum matures
Follicle develops

117
Q

LH- gland and function

A

Pituitary gland-
Ovary releases mature ovum into oviduct
Follicle become corpus luteum

118
Q

Hydrogen Carbonate indicator

A

Co2 presence means it will turn yellow. A lack of it means it turns purple.

119
Q

Photosynthesis starch test

A

Boil the leaf in ethanol, to remove chlorophyll.
Add drops of iodine.
Blue/Black color indicates Starch presence.

120
Q

How is the response to a shoot of light controlled

A

Auxin is produced at the tip of the shoot

Auxin diffuses down the shaded side of the shoot

Auxin produces cell elongation

So the cell bends towards the light ]

121
Q

homeostasis definition

A

The maintenance of a constant internal environment

122
Q

homeostasis 3 examples

A

sweating
shivering
reducing blood that goes near the skin

123
Q
A

Biology Edexcel (7 decks)

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