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Unit 2 Multicellular organisms Flashcards

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1
Q

What are chromosomes made up of?

A

2 Chromatids and opposite ends of the X shape and a Centromere that meets in the middle

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2
Q

What is a chromosome complement?

A

Every species of living organism has a number of chromosomes called it’s chromosome complement eg humans have 46 chromosomes (23 pairs)

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3
Q

What is the difference between haploid and diploid?

A

a cell which has 2 sets of matching chromosomes is known as diploid

a cell which has one set of chromosomes is called haploid these are sex cells

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4
Q

What happens with haploid cells for fertilisation?

A

sex cells must be haploid as the nuclei of two haploid cells (haploid sperm and haploid egg) fuse together during fertilisation to produce a diploid zygote

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5
Q

what is mitosis in cells?

A

mitosis is the process of producing new cells and provides new cells for the growth and repair of damaged cells while keeping the diploid chromosome complement

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6
Q

why do we need new cells?

A

new cells always need to be produced to replace damaged cells and allow growth to happen eg a skin cells life span is 2 weeks

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7
Q

what is the stages of mitosis?

A
  1. DNA of cell is duplicated
  2. Chromosomes become more visible, they shorten and thicken and are seen as a pair of chromatids
  3. chromosomes line up along equator of cell and spindle fibres attach to the chromosomes
  4. chromosomes pulled apart and spilt into separate chromatids and are moved to opposite ends of the cells
  5. nuclear membranes form around each region of DNA, cytoplasm divides between the 2 cells, the cell pinches in the middle and divides into two genetically identical daughter cells
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8
Q

what are stem cells?

A

stem cells are unspecialised cells, this means they have the potential to become different types of cells

stem cells can divide in order to self renew and they are involved in growth and repair

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9
Q

what is the hierarchy of the specialisation of cells?

A

cells —> tissues —> organs —> systems

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10
Q

what are the 2 parts of the nervous system?

A

The central nervous system(CNS) = Brain + spinal cord

Peripheral nerves = connect the CNS to all parts of body

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11
Q

What is the medulla?

A

The medulla is found at the bottom of the spinal cord

The medulla controls heart rate and breathing

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12
Q

What is the Cerebrum?

A

The cerebrum is the large folded area of the brain

The cerebrum is responsible for conscious thoughts, memory and emotion

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13
Q

What is the Cerebellum?

A

The Cerebellum is found at the real of the brain

The cerebellum controls balance and coordination movement

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14
Q

What are sensory receptors?

A

Sensory receptors are found in all parts of the
body, these detect sensory stimuli and produce a electrical signal which is picked up by sensory neurons that are carried to the CNS

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15
Q

how does information pass along neurons?

A

through electrical impulses

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16
Q

what are the three forms of neurons?

A

SIM
Sensory neurons
Inter neurons
Motors neurons

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17
Q

What do sensory neurons do?

A

Carry info from sensory receptors to CNS

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18
Q

What do inter neurons do?

A

Carry info BETWEEN sensory neurons and motor neurons within the CNS

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19
Q

What do motor neurons do?

A

Carry info from the CNS to effectors (muscles or glands)

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20
Q

What response do reflex reactions have?

A

an involuntary response, they have to be extremely fast so they bypass the brain and only travel through the spinal cord eg your hand burning

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21
Q

what is a synapse?

A

a synapse is a gap between each neuron that the electrical impulse has to cross to pass on its message

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22
Q

what are the chemicals that carry information across the synapse called?

A

neurotransmitters

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23
Q

what are hormones?

A

hormones are chemical messengers found in the endocrine system

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24
Q

what is the difference between hormones and neurons?

A

hormones are chemical messengers
neurons are electrical messengers

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25
what is the endocrine system?
the endocrine system is made up of endocrine glands that release hormones into the bloodstream, the hormones travel to their target organ
26
what are target organs?
target organs have cells with complementary receptor proteins for specific hormones
27
what is homeostasis?
the maintenance of constant internal environment eg keeping your blood glucose levels at certain levels
28
how is blood glucose regulation controlled?
blood glucose regulation is controlled by 2 hormones insulin and glucagon.
29
What happens when there is an increase in glucose concentration?
The pancreas releases insulin in response, glucose is taken into muscle and liver cells and stores as glycogen then there will be a decrease in glucose concentration
30
what happens when their is an decrease in glucose concentration?
pancreas releases glucagon in response, liver cells break down glycogen and release stored glucose, then glucose concentration increases
31
what are the male gametes in animals and plants?
animal - sperm plant - pollen
32
what are the female gametes in plants and animals?
animal - egg plant - ovule
33
what do gametes carry?
50% genetic information from mother 50% genetic information from father
34
how much chromosomes are in body cells, gamete cells and fertilised egg (zygote) cells?
body cells (diploid)- 46 chromosomes gametes (haploid)- 23 chromosomes fertilised egg (zygote) - 46 chromosomes
35
where are the gametes in plants produced for each parent?
males - pollen is produced in the anthers females - ovules is produced in the ovaries
36
where are the gametes in animals produced for each parent?
males - sperm is produced in the testes females - eggs are produced in the ovaries
37
what is the process of fertilisation?
fertilisation is when the nucleus of the haploid speed and the nucleus of the haploid egg fuse together to form a diploid zygote
38
what is variation?
variation is the differences that exist between members of the same species
39
what are the 2 forms of variation?
discrete variation - characteristics controlled by one single gene eg. eye colour continuous variation - characteristics controlled by more than one gene eg. height, shoe size
40
what are genotypes and phenotypes?
genotype - an indiviauais alleles for a particular characteristic phenotype - physical appearance
41
what is an allele?
an allele is the different form of a gene which produces phenotypes genetic info is stored in genes, alleles determine which form of that gene you have (eg blue eye colour)
42
what are dominant alleles?
dominant alleles always produce a certain phenotype they are represented by a capital letter e.g A
43
what are recessive alleles?
recessive alleles aren’t shown in the phenotype if a dominant allele is present represented as a lower case letter e.g a
44
what does homozygous mean?
an individual who has inherited two of the same alleles for a gene these are represented as either 2 capital letters or 2 lower case letters e.g AA or aa
45
what does heterozygous mean?
an individual who has inherited two different alleles of a gene this is represented by a capital letter and a lower case letter e.g Aa
46
will offspring always follow the expected phenotype ratio?
no because fertilisation is random
47
what do plants need water for?
to maintain turgor for photosynthesis to keep cool
48
how does water enter a plant?
water enters the root hairs by osmosis water molecules move from a area of high concentration to an area of low concentration inside the root hair cells
49
what is the function of root hairs on plants?
to increase the surface area so more water molecules and minerals can be taken up
50
what are xylem?
xylem are tubes that plants use to transport water up through the plant, they are hollow dead tubes supported with lignin rings
51
what are phloem cells?
phloem is used to transport sugar up and down the plant unlike xylem they are alive they have cells called companion cells to provide energy
52
what are the three structures within the phloem?
Sieve plate Sieve tube Companion cell
53
what is the vein made up of in a plant?
The Xylem and the Phloem
54
what is the cuticle in a lead structure?
the cuticle is a waxy protective layer that cuts down water loss
55
what is the epidermis (upper and lower) in a leaf structure?
the epidermis is like a skin where the stomata and guard cells are found
56
what is the palisade layer in the leaf structure?
the palisade layer is made up of tall, cylinder shaped cells where most photosynthesis takes place
57
what is the spongy mesphyll layer in the leaf structure?
this consists of irregularly shaped cells which don’t fit together, this will create space between the, for gases to move around
58
what are stomata?
stomata are small pores found on the underside of the leaf they let water vapour and gassed in and out of the leaf
59
what do guard cells do with the stomata? i
the stomata is surrounded by 2 guard cells which control, the opening and closing of the stomata
60
what happens when a plant has a higher level of water?
the guard cells will become turgid and circe out opening the stomata which allows CO2 in and O2 out water also evaporates out the stomata
61
what happens when a plant has a low level of water?
the guard cells lose water and close gas exchange can’t take place and water is not lost
62
what is the process of movement of water vapour out the stomata known as?
transpiration
63
what is the process of transpiration?
water is taken into the root hairs from the soil by osmosis water goes up through the plant through the xylem tubes water is lost to the atmosphere by evaporation through an open stomata
64
what can affect the rate of transpiration?
increases rate of transpiration - high light intensity, warm temperatures, wind decreases rate of transpiration - low light intensity, cool temperatures, humidity
65
what are arteries?
think elasticated walls, that can withstand high pressure Arteries carry blood Away from heart
66
what are veins (blood)?
contains valves to prevent back flow of blood carry blood to heart
67
what are capillaries?
thin, one cell thick walls to allow gas exchange very low blood pressure
68
what are the 4 types of blood cells?
red blood cells white blood cells platelets plasma
69
what are red blood cells?
red blood cells are specialised to transport oxygen contain lots of protein called haemoglobin, that bind to oxygen to produce oxyhaemoglobin biconcave shape to maximise surface area no nucleus small and flexible to squeeze through capillaries
70
what are white blood cells?
Part of the immune system: contains phagocytes that engulf and digest pathogens by phagocytosis contains lymphocytes that produce antibodies that destroy pathogens
71
what are platelets?
they stop us bleeding circulate around the blood and clump together when they find damaged blood cells as the clot dries out a scab forms
72
what is plasma?
liquid component of blood makes up over 50% of your blood transports carbon dioxide, hormones and digested food
73
what is the heart?
the heart is responsible for pumping blood around the body deoxygenated blood taken to lungs to pick up oxygen oxygenates blood transported around the body
74
what are the 4 chambers of the heart?
right atrium right ventricle left atrium left ventricle
75
what are the blood vessels of the heart?
Vena Cava Pulmonary Artery Pulmonary Vein Aorta Coronary artery
76
what is the function of the vena cava in the heart?
brings deoxygenated blood from body to heart
77
what is the function of the pulmonary artery in the heart?
takes blood to the lungs
78
what is the function of the pulmonary vein in the heart?
brings oxygenated blood from the lungs to the heart
79
what is the function of the aorta in the heart?
pumps oxygenated blood around the body
80
what is the function of the coronary artery in th heart?
provides the heart with its own blood supply
81
Why is the muscular wall of the left ventricle thicker than the right?
because the left ventricle has to pump blood all around the body rather than just around the lungs
82
what is the structure of the lungs?
trachea bronchus bronchiole alveoli
83
what is the alveoli?
the alveoli is the site of gas exchange in the lungs
84
what makes the alveoli good at gas exchange in the lungs?
thin lining - it has thin lining so gas can quickly diffuse through it large surface area - increases the area for gas to diffuse good blood supply - dense capillary network so large volume of gas can be exchanged
85
what is the small intestine?
once food is digested it’s nutrients need to be absorbed, the small intestine has specialised structures called villi to help absorption
86
why are villi so good at absorbing food or nutrients?
thin walls - food absorbed quickly and easily blood capillaries- absorbs amino acids and glucose lacteal - absorbs fatty acids and glycerol

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