Answers to IGCSE Worksheets
Cells, Tissues and Organs
a. Cell, tissue, epidermis, organ, systems, excretory
system.
b. specialised, red blood cell, division of labour,
nervous and endocrine
c. palisade cell, chloroplasts, leaf, epidermis, xylem
Biological Molecules and Food Tests
Across
2 water
4 starch
6 biuret
8 blood
9 orange
10 glucose
11 cholesterol
14 DNA
15 condensation
16 emulsion
18 blue-black
20 lipids
21
22 haemoglobin
Down
1 purple
3 amino acid
5 hydrolysis
7 protein
12 sucrose
13 benedicts
17 milky
19 urine
Movement of molecules in and out of cells
a. osmosis
b. partially permeable membrane
c. water has entered by osmosis making the cell turgid
d. solution c has a lower water potential and water has
left the cell leaving it flaccid.
2. Experiment
a. Graph 4 marks = Axis (x = Concentration of sugar
solution 0.0-10.0 and y = % change in mass of potato
cylinders +10 - -20), Scale, Plotting, Line
b. 0.24 Moles
c. When the solution and the cytoplasm inside the cell
are in equilibrium (no net movement of water
molecules = 0 in the change in mass). Then the
concentration inside the cytoplasm must equal the
concentration of the sugar solution.
d. To repeat the test for reliability.
e. To remove any water that would give a incorrect
mass reading.
f. Extrapolate the graph and read
3. a. i. Turgid cells, photosynthesis, metabolic
reactions, movement of nutrients
ii. The water potential gradient is lower outside the
plant than inside the cells – hence water will leave the
cells (flaccid) and the plant will wilt.
b. i. Active process
ii. Energy is required for active process, which would
deprive the plant of the energy needed for growth.
iii. Magnesium for chlorophyll and nitrogen for proteins
Fill in the missing word
Cytoplasm, partially permeable membrane, explode,
lower, wall,
Amino acids, diffusion, concentration gradient, active
process, energy, against
Carbon dioxide, diffusion, respiration.
Food and Diet in Humans
4. a. Quorn has little fat and 0 cholesterol – reduces
risk of obesity and heart attacks, high in fibre
(improves digestion) and low in energy content so not
fattening.
b. (355x 2.5) + (3600/10) + 575 = 1822.5 kJ
5. a. Black
b. Biuret
c. Sample D
d. Control and to see the negative colour for the tests
e. Dissovle the food in ethanol, add water and a milky
solution is a positive test for fat.
f. Obesity that can lead to CHD or diabetes
Crossword Across
1 scurvy
3 salt
4 calcium
7 carbohydrate
9 steroid
10 protein
11 fat
13 respiration
14 balanced
15 iron
16 membrane
Down
2 ricketts
3 sucrose
5 cholesterol
6 baked beans
8 malnutrition
12 fibre
Digestion and Absorption pg 45
1. .
a. A= Jaw
b. The jaw chews the food and the salivary gland
adds saliva to make a bolus that is easy to swallow.
c. C is the epiglottis that cuts off the trachea.
d. D is the oesophagus and food moves by
peristalsis where the circular and longitudinal
muscles alternately squeeze the food down the
channel.
e. Small intestines are very long (7m) and have
villi with micro-villi to increase the surface area.
f.
.
i.
Glycogen
ii.
Hepatic portal vein
iii.
Hepatic vein
iv.
Bile emulsifies fats - this increases the
surface area of the lipids so that digestion
can occur easier. Lipids are hydrophobic
and do not dissolve in water and therefore
form large clumps called micelles.
g.
i.
Pancreatic duct
ii.
Proteases works on proteins etc.
h. E= Re-absorb water, breakdown fibre
F = gets rid of solid waste (egestion)
2. .
a. Inside A = Black B = Red Brown
b. Starch was broken down in tube B by the
amylase but remained in tube A because the
amylase was boiled and the enzyme was
denatured.
c. Test tube B for a reducing sugar as maltose or
glucose should be present as starch was
broken down.
d. .
i.
X= Epithelial cells
Y = Blood capillaries
Z = Lacteal
ii.
Small intestines specifically the ileum.
iii.
X
iv.
To absorb the fatty acids
3. .
a. .
i.
X = Molar
Y = Canine
Z = Incisor
ii.
X = grinding food and Z for cutting food
b. Calcium and Vitamin C
c. .
i.
Sugar sticks to the enamel, bacteria feed
on the sugar and produce an acid that
eats a hole through to the dentine. The
bacteria can enter into the dentine to
continue the decay.
ii.
Brush teeth twice a day, use mouthwash,
go to dentist regularly, avoid sugary
foods, floss etc.
4. .
a. Lipase
b. Acid
c. .
i.
8.7 – 8.1 = 0.6
8.1 – 7.7 = 0.4
ii.
0.6 + 0.4 = 1 / 4 = 0.25 pH per min
Bile is an emulsifier and increases the
surface area of the fat in the milk.
5. .
a. .
i.
Protease
ii.
Amino acids
b. The effect of pH on the activity of Protease
c. Stomach
d. So the small products of digestion can be
absorbed into the blood supply and assimulated
in our body cells.
6. .
A – 12
B – 22
C – 21
D – 17
E–3
F – 13
G – 19
H–1
I – 20
J – 18
K–2
L – 14
M–9
N – 16
O–6
P–8
Q–7
R–5
S–4
T – 15
U – 11
V - 10
Useful Microbes Crossword
Across
1 biogas
4 sewage
8 chymosin
9 GMO
10 acid
13 bacteria
15 mycoprotein
16 vector
17 restriction
19 penecillin
20 lipase
22 acetic acid
23 alkanes
24 lactobacillus
Down
1 Brewing
2 plasmid
3 whey
5 protease
6 dioxide
7 lactic
11 carbon
12 fermentation
14 amylase
15 methane
18
21 yeast
Matching Terms
Distillation
Fermentation
Bioreactor
Chymosin
Carbon dioxide
Whey
Hops
Yeast
Alcohol
Pasteurisation
Lactobacillus
Acetobacter
Sterilisation
Mycoprotein
Bacterium
Photosynthesis
Match the terms
A-4
B-10
C-15
D-1
E-13
F-8
G-5
H-14
I-12
J-6
K-2
L-9
M-11
N-7
O-3
Plant Transport - Fill in the missing words
Osmosis
Hairs
Surface area
Ions
Nitrate
Diffusion
Active transport
Support
Solvent
Photosynthesis
Xylem
PhloemVascular
1a i The plants absorb nitrate so removed the ions
from the soil. Usually when organisms decay the
nitrogen would be put back in the soil but the plants
were removed.
ii. Add synthetic fertilisers or natural manure
b. These are leguminous plants and they have
nitrogen fixing bacteria in their root nodules that take
atmospheric nitrogen and make it available to the plant
as ammonia.
Transport in Animals
6. a. i glucose and oxygen
ii. carbon dioxide
b. i. Cardiac muscle
ii. it will contract
iii. the blood in the left ventricle will be forced to leave
through the semi lunar valves and into the aorta to be
pumped around the body.
c i there is a build up of cholesterol in the arteries due
to a fatty diet or smoking.
Ii Below point B
d. Veins have a large lumen to allow the blood to flow
back to the heart and they have valves to stop the
blood flowing backwards.
Crossword Across
1 cholesterol
3 pacemaker
4 muscle
7 blood pressure
9 arteries
10 coronary
12 semilunar
15 tendon
16 ventricle
18 left
19 pulmonary
21 atrium
22 veins
Down
1 capillaries
2 valve
5 smoking
6 vena cava
8 exercise
11 diastole
13 systole
14 aorta
17 bypass
19 pulse
20 right
Defence Against Disease
Excretion and Osmosis pg 83
4. a. It is killed or only a part of it is used.
b. The vaccine has antigens on it that bring about an
immune response from the host. This means
antibodies that are specific to that antigen are
produced by lymphocytes to help destroy the antigen.
At the same time the lymphocytes produced are stored
so the next time the antigen enters the body the
immune response will be quicker.
1. a. Water gain = 1000 + 1300 = 2300cm 3
- Water loss = 450 + 500 + 150 = 1050 cm 3
Loss in urine = 1200 cm 3
b. The hypothalamus registers a decrease or increase
in the water in blood. It either releases more or less
ADH. If the water content is low in blood more ADH is
released and more water is reabsorbed from the
kidney tubule (loop of Henle) into the capillaries
surrounding the nephron. This is a negative feedback
as the opposite effect occurs from the stimulus.
5. a. i. Section of DNA (gene) that codes for the
surface antigen
ii. surface antigen
b. Even though it was stopped from reproducing it was
still a live vaccine that contained the Hepatitis B virus,
which could be passed on.
Fill in the missing words
Blood loss
Pathogens
Disease
Platelets
Proteins
Fibrinogen
Fibrin
Red blood cells
Haemophilia
Breathing and Gas Exchange
Fill in the missing words
Pulmonary
Respiration
Energy
Carbon dioxide
Hydrogencarbonate
Capillaries
Thin
Surface area
Alveoli
Carbon dioxide
Oxygen
Pulmonary
Left atrium
Respiration and the Release of Energy
5. a. false
b. true
c. false
d. true
e. true
f. true
g. false
h. true
i. true
j. true
k. true
Fill in the missing words
Living cells
Glucose
Oxygen
Energy
Aerobic
Movement
Growth
Heat
c.
i.
Advantages of a dialysis machine over kidney
transplant are;
 There may be rejection of the kidney
 The person has to take immune-depressant drugs
that can lead to illness
 The person is under constant medical supervision
with dialysis
ii.
Disadvantages are;
 Constant stay in hospital for the dialysis that
interferes with lifestyle
 Kidneys are more efficient at removing waste from
blood
 There is a risk the urea level will reach lethal high
levels.
2. a.
i.
They are too large to go through the membrane
ii.
Glucose is small enough to be in the filtrate but is
reabsorbed in the tubule as it is an important
nutrient. The capillaries around the nephron take
the glucose back to the body to be used for
storage or respiration.
b. ADH controls the re-absorption of water in the
kidney. On a hot day whilst exercising more water is
lost through sweat thus more water needs to be
replaced in the body. The increased ADH increases
the re-absorption of water in the loop of Henle.
3. a.
Excretion is the removal of waste products from
the body
ii.
Egestion is the removal of undigested material
from the body
i.
b.
i.
ii.
Liver
Proteins (amino acids).
c.
Q = Renal artery
R = Renal vein
S = Ureter
T = Urethra
d.
Component of Blood
Glucose
RBCs
Salts
Urea
Water
WBCs
glucose in the blood more than if a person is
sedentary.
Present in Urine
X
X
v
v
v
x
b. ‘Hypo’ means there is too little glucose and the
person will require glucose immediately. Sugar will
provide it. Starch contains glucose but takes time to
break it down.
c. The hormone glucagon is produced by the pancreas
to convert glycogen in the liver to glucose.
4.
a. The kidneys are not working so urea is not
removed
b. They have more room to increase their urea
concentration before the next dialysis treatment
= more time between treatments
c. The patient is given immune-suppressant drugs
to help prevent the patient from rejecting the
kidney. They will have to be given antibiotics to
help fight any infections because they are
immune-suppressed.
d. Negative feedback is when the reaction is opposite
to the situation e.g. when blood sugar is high insulin is
released to convert glucose to glycogen, which lowers
the blood sugar.
Fill in the Gaps
Hormones
Endocrine organ
Bloodstream
Target organ
Adrenaline
Trachea
5. ACROSS
2 urine
3 urea
4 henle
5 bladdar
8 filtration
9 renal artery
10 sphincter
13 excretion
14 plasma
15 glucose
16 bowmans
18 liver
19 kidney
20 dialysis
1.
a.
b.
c.
d.
e.
f.
2.
a.
b.
c.
d.
DOWN
1 nephron
2 urethra
3 ureter
6 renal vein
7 diuretic
11 hormone
12 amino acids
14 protein
17 anti
Hormones and the Endocrine System
a. i. Diabetics cannot produce enough or any insulin
themselves from the pancreas or it doesn’t result in the
uptake of glucose.
ii. as insulin converts glucose to glycogen too much
insulin will remove all the glucose from blood.
iii. Exercise requires movement of the muscles, which
requires energy. This energy is from aerobic
respiration that requires glucose. This reduces the
e.
The Nervous System and Co-ordination pg 92
.
A
D
A
E
C
B
.
4
4
3 x 3 + 1.6 = 10.6 units = 210 – 80 = 30 mg per
100 cm3 over the limit
Co-ordination impaired, reaction time increased,
feeling of invincibility etc
10 hours and 10 minutes
f. Cirrhosis
3.
i.
ii.
iii.
iv.
Road traffic accidents
5/20 = 1/5
Damage central nervous system – cerebral
All nerves end in the spinal column so she has
damaged nerves that affect her lower body but not
her upper body.
4. .
a. A= Sensory neurone
B = Spinal column
C = Relay neurone
D = Motor neurone
E = Synapse
b. The electric signal reaches the end of the neurone
and stimulates the release of chemicals called
neurotransmitters. If enough chemicals are
released that cross the gap (synapse) then the
electrical signal is stimulated on the next neurone.
c. Stimulants = caffeine chemical persists, heroin and
nicotine copies chemical, cocaine prevents
removal thus stimulating an electrical signal.
Sedative = marijuana which blocks the
chemical and stops the electrical signal.
5. .
a. .
i.
ii.
iii.
iv.




No of
Heart rate (beats per min) Mean
coffees
drunk
0
74, 76, 72, 72, 78, 68
74
1
78, 78, 82, 72, 72,70
75
2
78, 78,79, 87, 80, 72
79
3
80, 82, 78, 81, 78, 76
79
4
76, 78, 88, 90, 88, 86, 78
83
5
80, 90, 88, 88, 94, 92
89
X-axis = coffees drunk , y axis = mean heart rate
(beats per min), scale 70-90
Yes as increasing cups of coffee increased heat
rate.
Precautions;
Each person should have been tested for each
cup of coffee number otherwise different people
may have different heart rates.
Age and sex should be consistent in the study
group.
Timings exact for drinking coffee and heart rate
measured after.
Coffee concentration and volume kept the same.
b. This trial cannot be done in real life thus data
collected from women who are heroin addicts and
get pregnant can be used to support this
investigation.
6. .
a. A = Relay neurone – takes the signal from the
sensory neurone to the motor neurone so the
effector is stimulated.
b. Synapse
c. .
i.
Electrical
ii.
chemical
d. .Unnecessary
e.
i.
The limb would not sense the hot surface
ii.
The effector would not react
f. No as the message would not be received
g. C = Neurone
D = Myelin sheath
E = Cell body
F = Node of Ranvier
G = Dendrites
Match the words
A–5
B–9
C–1
D – 10
E–2
F–3
G–6
H–4
I–7
J–8
Human Reproduction and Growth pg 107
1. .
a. A = Vas deferens
B = Urethra
C = Testis
D = Scrotum
E = Penis
b. C
c. F (prostate gland)
d. C
e. B
f. A
2. e, a, d, b, f, c
3. .
a. A = Oviduct
B = Ovary
C = Uterus
D = Endometrium
E = Cervix
F = Vagina
b. X = Oviduct
Y = Uterus wall = endometrium
c. .
i.
The diaphragm is inserted before the cervix so
sperm cannot enter the uterus and oviduct
ii.
The pill thickens the lining of the uterus so the
body thinks it is pregnant. Also the pill prevents
ovulation from occurring.
4. .
a. .
i.
Urea, carbon dioxide
ii.
Mothers’ capillaries and foetuses’ capillaries
come in close contact together in the placenta.
There is a large surface area in the placenta to
allow maximum contact.
iii.
Kidneys to remove urea, Liver to deaminate
proteins, stomach to digest proteins, small
intestines to digest food and absorb nutrients etc
b. .
i.
Amniotic fluid is to protect the baby in the watery
environment.
ii.
Down’s Syndrome
c. .
i.
bar graph
ii.
% increase 30-34 = 4.9 - 0.5 = 4.4 / 0.5 = 8.8
% increase 45-49 = 27.2 – 0.5 = 26.7 / 0.5 = 53.4
iii.
HRT benefit reduces the onset of menopause and
its symptoms e.g. hot flushes, tiredness, mood
swings. HRT disadvantages can lead to breast
cancer.
5. .
a. .
i.
A hormone is a chemical substance, produced by
a gland, which alters the activity of one or more
specific target organs and is then destroyed by the
liver.
ii.
Carried by the blood
b. Safe to have sex without a contraceptive
c. Oestrogen stimulates ovulation and maintains
the lining of the uterus. LH triggers ovulation and
matures the corpus luteum to produce
progesterone to maintain the endometrium.
d. Benefits 99% effective if used correctly, reduce
period pain. Disadvantages – can put on weight,
increase risk of cervical cancer
6. .
a. Head develops e.g. face and ears, Foot gets toes
b. .
i.
7mm at 6 weeks and 95mm at 6 months
ii.
95/7 = 13.6 times
7. .
a. P = Ovary
Q = Cervix
R = Vagina
b. The oviducts are closed so the ovum cannot be
fertilised and travel to the uterus.
c.
i.
Endometrium in uterus
ii.
To replicate the journey down the oviduct where
the zygote is dividing and forming a ball of cells.
d. Implantation after day 14 when the uterus is fully
thickened and progesterone is starting to
increase to maintain the wall of the uterus.
Matching Pairs
A – 13
B–9
C–8
D–1
E–3
F – 18
G – 15
H–2
I – 10
J – 20
K–5
L–6
M–7
N–4
O – 17
P – 11
Q – 14
R – 12
S – 16
T – 19
Cell Division and Human Life Cycle
5. a. i. Meiosis
ii. haploid nucleus
iii. zygote
iv. if a boy he will have an X and a Y chromosome and
a girl has two X chromosomes
b. i. Ovary
ii. oviduct
iii. uterus
Matching Pairs on Cell Division
A–7
B–5
C–8
D–6
E–
F–9
G–2
H – 10
I–3
J–4
Sensitivity and Movement in Plants
Match the Terms
A–5
B–7
C–6
D–9
E–3
F – 10
G–4
H–1
I–2
J–2
c. i. Shoot up root down
ii. root response is positive geptropism
where the auxin gathered on the underside and
reduced the growth of the cells so the root grows
down.
shoot response is a negative geotropism and the auxin
has stimulated the growth of cells causing them to
elongate so the shoot bends upwards.
iii. Gravity was felt on all sides equally.
Reproduction in Plants
Across
4 stigma
7 fruit
9 hermaphrodite
10 wind
12 seed
13 anther
15 nectary
17 ovary
18 dispersal
19 pollination
20 insect
22 variation
23 filament
24 tuber
Down
1 egg
2 competition
3 sepal
5 asexual
6 fertilisation
8 runner
11 petal
14 germination
16 pollen
21 style
Enzymes pg 35
ii.
iii.
iv.
Bar Chart
Sample A for Liver (8 cm 3) is about twice the
volume of oxygen collected than for potato (4.5
cm3).
The larger surface area of the chopped pieces of
liver provided more catalase and therefore there
was more oxygen produced as more hydrogen
peroxide was broken down.
b. C and D are controls as the enzyme was
denatured when the potato and liver were boiled and
therefore proves that the enzyme has to be present
to breakdown hydrogen peroxide.
1.
i.
Proteins
ii.
Pathways
iii.
Catalysts
iv.
Specific
v.
Denatured
2. .
a. Temperature
b. Amount of catalase (potato pieces)= same sizes
use a cork borer, volume of hydrogen peroxide =
burette
c. Amount of oxygen produced = movement of the
manometer (mm)
d. Boiled potato to denature enzymes
e. Identify anomalies and reduce errors when
collecting gas.
3. .
a. Slow increase to 25o C as temperature is low and
the KE of the particles is low. Then steep
increase to 35o C (optimum temperature). Steep
decrease to zero oxygen consumption at 65 o C
as enzymes have denatured.
b. Input = temperature
Outcome = oxygen consumption mm per s
Fixed = number and size of maggots, availability
of oxygen, removal of carbon dioxide.
4.
a. Enzyme is a protein that acts as a biological
catalyst.
b. .
i.
Carbohydrases to breakdown carbohydrates,
proteases to breakdown proteins and lipases to
breakdown lipids can all be present in Biological
washing powders that turn large coloured
molecules into small colourless molecules so the
stains are removed.
ii.
If temperature is too high then the enzymes will be
denatured and no longer breakdown the large
molecules.
iii.
40o C as this is the optimum temperature at which
many enzymes work.
c. Enzymes can be made mass produced in
fermenters. Bacteria can cultured by providing the
optimum conditions e.g. food, water, temperature,
oxygen so that they can grow and then the
enzymes can be extracted.
5. a.
i.
Tissue
Vol of Oxygen collected / cm 3
A
B
C
D
Potato
4.5
6.5
0
0
Liver
8
10
0
0
c. Oxygen relights a glowing splint.
6.
a. Immobilised means that it cannot move and
stays on the plastic.
b. The oxygen concentration will decrease as it is
used during the reaction with glucose in the
presence of glucose oxidase.
c. The Transducer converts the oxygen
concentration into an electrical signal.
Across
1 Denaturation
5 Metabolism
8 Hydrogen
9
10 Substrate
13 Inhibitor
15 Protease
16 Catalyst
17 And
18 Lock
19 Pepsin
20 Optimum
Down
2 Temperature
3 Lipase
4 Amylase
6 Active
7 Key
10 Site
11 Activator
12 Catalase
14 Product
Germination and Plant Growth
Across
3 fertilisation
4 amylase
5 embryo
7 testa
8 radicle
9 ovule
10 cotyledon
13 flower
15 plumule
16 enzymes
17 water
Down
1 germination
2 gamete
6 oxygen
11 dormant
12 fruit
14 lipase
15 pollen
DNA Genes and Proteins
Across
2 amylase
4 protein
5 genotype
7 mutagen
10 chromasome
13 messenger
14 bases
15 aminoacid
16 replication
18 phenotype
19 haemoglobin
20 gene
Down
1 bacterium
3 mutation
6 nucleus
8 transcription
9 ribosomes
11 radiation
12 double helix
17 allele
Variation and Selection pg 133
1. 1 – A
2–A
3–A
4–N
5–N
6–N
7–A
8–A
2.
a. 120
b. Histogram B as the number of limpets measured
was much higher giving a more reliable result.
c. Area 2 as the bases of the shells was larger so
they can cling on better.
d. Continuous
e. Height
3. .
a. Statement 1 – 3, 4
2–2
3–1
b. .
i.
The paint spot was small
ii.
The snails with more faded paint had spent
longer in the sun as the paint was light sensitive.
iii.
So that there is an equal chance that the light will
reach that part of the snail.
iv.
They are camouflaged with the dark
surroundings
4. .
a. Desert as it has adaptions suited to a dry climate
b. It has reduced leaves to needles, a large stem to
store water and deep roots to reach water.
c. A – 4
B–2
C–6
D–1
E–5
F–3
Fill in the Gaps
Discontinuous
Blood Grouping
Continuous
Body mass
Discontinuous
Genotype
Continuous
Environmental
Genotype
Phenotype
Evolution
Mutation
Effects of Environment
Genes
Crossing over
Independent assortment
Fertilisation
Natural selection
Evolution
Genes
Patterns of Inheritance
b. they don’t get enough oxygen to their cells for
respiration and the production of energy
c. sickle-cell anaemia
d. mutation
e. UV radiation,
5. i recessive otherwise the parents and the first
child would have the disease.
ii. Parents Phenotype Carriers
Parents Genotype Ff Ff
Gametes F f
Offspring
F
f
F
FF
Ff
f
Ff
ff
Phenotypes 1 normal : 2 carriers : 1 cystic fibrosis
1 in 4 chance 3:1 ratio
c. i. Identify and cut gene for normal DNA – Insert
into virus RNA – multiply virus
ii. danger using viruses as may change other
genes, interfering too much with nature, allergies
may arise
Fill in the Gaps
Mendel
Garden pea
Stamens
Stigma
Insects
Tall
Height
Homozygous
Tall
Dominant
1:1
Mendel
DNA
Genes
Chromosomes
Nucleus
Ecology and Ecosystems
Across
3 kiolojoule
5 ecosystem
6 quadrat
9 consumer
10 heterotroph
12 community
14 food chain
17 herbivore
18 habitat
19 omnivore
Down
1 autotroph
2 producer
4 population
7 transect
8 carnivore
11 sunlight
13 carbon
14 food web
15 biomass
16 sample
Recycling of Nutrients
Across
1 denitrification
3 photosynthesis
4 carbon dioxide
5 nitrification
8 fixation
9 nodules
12 respiration
14 fungi
15 bacteria
16
17 excretion
18 active
19 amino acid
Down
2 eutrophication
6 enzymes
7 leaching
10 protein
11 combustion
13 nitrate
Human Impacts on the Environment
Fill in the Gaps
Infra red
Methane
Carbon dioxide
Pests
Photosynthesis
CFCs
Ultra violet
Cancer
Mutation
Acid rain
Mesophyll
Nitrate
Pesticides
Acid rain
Batteries
Motor oil
CFCs
Conservation
Across
1 recreation
4 panda
6 food web
8 restoration
9 CITES
13
14 habitats
16 breeding
17 tiger
18 resources
19 zoo
20 elephant
Down
2 captive
3
5 agriculture
7
10 rhinoceros
11
12 turtles
15 DDT
Farming and Food Production
Match the Term with the Definition
A–E
B–I
C–J
D–G
E–A
F–C
G–D
H–B
I–H
J–F