Unit 2 - Multicellular Organisms

Question 1

how many chromosomes are in the human body

Answer 1

46 chromosomes or 23 pairs

Question 2

what type of cells are diploid

Answer 2

cells with two sets of chromosomes

Question 3

what type of cells are haploid

Answer 3

cells with one set of chromosome

Question 4

what is mitosis

Answer 4

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

Question 5

why do cells perform mitosis

Answer 5

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

Question 6

what are the steps of mitosis

Answer 6

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

Question 7

what does the central nervous system (CNS) consist of

Answer 7

The Brain and Spinal Cord and other nerves

Question 8

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

Answer 8

cerebellum

Question 9

long bit on the bottom of the brain

Answer 9

medulla

Question 10

top of the brain

Answer 10

cerebrum

Question 11

what does the medulla control

Answer 11

it controls the rate of breathing and heart rate

Question 12

what carries information around the body to the CNS

Answer 12

Sensory Nerves

Question 13

what carries impulses from the CNS to the effectors

Answer 13

Motor Nerves

Question 14

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

Answer 14

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

Question 15

what is the correct order of neurons in a reflex arc

Answer 15

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

Question 16

what is a synapse

Answer 16

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

Question 17

what happens when an impulse reaches a synapse

Answer 17

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

Question 18

what is a reflex action

Answer 18

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

Question 19

what are hormones

Answer 19

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

Question 20

what is a target tissue

Answer 20

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

Question 21

how does the body regulate blood glucose levels

Answer 21

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

Question 22

where is insulin produced

Answer 22

the pancreas

Question 23

what catalyses the glucose to glycogen reaction

Answer 23

insulin

Question 24

where is glucagon produced

Answer 24

the pancreas

Question 25

what is the function of glucagon

Answer 25

glucagon activates the conversion of glycogen to glucose

Question 26

when blood sugar levels drop what hormone is released from where

Answer 26

glucagon from the pancreas

Question 27

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

Answer 27

insulin from the pancreas

Question 28

what type of cells are gametes

Answer 28

haploid they are also the body's sex cell

Question 29

what happens during sexual reproduction

Answer 29

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

Question 30

what is the site of sperm production

Answer 30

the testes

Question 31

site of egg production

Answer 31

the ovaries

Question 32

what are the steps leading to fertilisation

Answer 32

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

Question 33

what is variation

Answer 33

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

Question 34

what are the two types of variation

Answer 34

Discreet Variation and Continuous Variation

Question 35

what is the difference between continuous and discreet variation

Answer 35

discreet variation cant be measured whereas continuous variation can

Question 36

give examples of discreet variation

Answer 36

hair color, eye color, weight

Question 37

give examples of continuous variation

Answer 37

height, shoe size,

Question 38

what factors effect discreet variation

Answer 38

inherited characteristics (genes)

Question 39

what factors effect continuous variation

Answer 39

environmental factors

Question 40

what is a phenotype

Answer 40

the outward appearance of a gene

Question 41

what is a genotype

Answer 41

genetic information passed on from generation to generation

Question 42

what make up a gene

Answer 42

alleles