Unit 2 - Multicellular Organisms Flashcards

1
Q

how many chromosomes are in the human body

A

46 chromosomes or 23 pairs

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2
Q

what type of cells are diploid

A

cells with two sets of chromosomes

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3
Q

what type of cells are haploid

A

cells with one set of chromosome

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4
Q

what is mitosis

A

mitosis is the process of a nucleus dividing into two daughter nuclei, each which have the same amount of chromosomes as the original.

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5
Q

why do cells perform mitosis

A

mitosis provides new cells for growth and repair of damaged cells whilst maintaining diploid chromosome compliment.

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6
Q

what are the steps of mitosis

A
  1. chromosome replicates to form two identical chromatids joined by a centromere.
  2. the nuclear membrane disappears and spindle fibres form.
  3. each chromosome becomes attached by its centromere to one of the spindle fibres at the equator.
  4. the spindle fibres contract causing the centromere to split and one chromatid from each pair moves to opposite poles.
  5. a nuclear membrane forms around each group of chromatids completing nuclear division.
  6. division of the cytoplasm forms two identical daughter nuclei
  7. each new cell undergoes a period of cell growth
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7
Q

what does the central nervous system (CNS) consist of

A

The Brain and Spinal Cord and other nerves

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8
Q

whats that bit of the brain thats hanging off of the end

A

cerebellum

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9
Q

long bit on the bottom of the brain

A

medulla

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10
Q

top of the brain

A

cerebrum

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11
Q

what does the medulla control

A

it controls the rate of breathing and heart rate

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12
Q

what carries information around the body to the CNS

A

Sensory Nerves

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13
Q

what carries impulses from the CNS to the effectors

A

Motor Nerves

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14
Q

what are the three types of neurons and their position in the body

A

sensory neuron - from the receptors to the CNS
inter neuron - within the CNS
motor neuron - from the CNS to the effector

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15
Q

what is the correct order of neurons in a reflex arc

A

stimulus, sensory neuron, inter neuron, motor neuron, effector.

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16
Q

what is a synapse

A

a synapse is a tiny space between the axon ending and sensory ending between two neurons

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17
Q

what happens when an impulse reaches a synapse

A

chemicals diffuse across the synapse between two neurons this triggers an impulse at the sensory end of the neuron

18
Q

what is a reflex action

A

a reflex action is a rapid, automatic involuntary response to a stimulus.

19
Q

what are hormones

A

a hormone is a chemical messenger secreted directly into the bloodstream endocrine glands

20
Q

what is a target tissue

A

a target tissue is a group of cells that have complementary receptor proteins for specific hormones.

21
Q

how does the body regulate blood glucose levels

A

the body uses the liver as a storehouse, it can store up to 100g of glucose converted into glycogen which can be added or removed depending on supply and demand

22
Q

where is insulin produced

A

the pancreas

23
Q

what catalyses the glucose to glycogen reaction

A

insulin

24
Q

where is glucagon produced

A

the pancreas

25
Q

what is the function of glucagon

A

glucagon activates the conversion of glycogen to glucose

26
Q

when blood sugar levels drop what hormone is released from where

A

glucagon from the pancreas

27
Q

when blood sugar level rises what hormone is released and from where

A

insulin from the pancreas

28
Q

what type of cells are gametes

A

haploid they are also the body’s sex cell

29
Q

what happens during sexual reproduction

A

the fusion of two gamete nuclei to produce a diploid zygote which divides to form an embryo.

30
Q

what is the site of sperm production

A

the testes

31
Q

site of egg production

A

the ovaries

32
Q

what are the steps leading to fertilisation

A
  1. an egg is released from the ovary
  2. the egg is then picked up from the oviduct by cilia
  3. egg is moved along the oviduct by the hair-like cilia
  4. the sperm cell will then fertilise the egg
33
Q

what is variation

A

variation is the word used when describing differences in a species which are not physical accidents

34
Q

what are the two types of variation

A

Discreet Variation and Continuous Variation

35
Q

what is the difference between continuous and discreet variation

A

discreet variation cant be measured whereas continuous variation can

36
Q

give examples of discreet variation

A

hair color, eye color, weight

37
Q

give examples of continuous variation

A

height, shoe size,

38
Q

what factors effect discreet variation

A

inherited characteristics (genes)

39
Q

what factors effect continuous variation

A

environmental factors

40
Q

what is a phenotype

A

the outward appearance of a gene

41
Q

what is a genotype

A

genetic information passed on from generation to generation

42
Q

what make up a gene

A

alleles